'The Hobbit' of today is a product of quite a bit of textual evolution, with several layers of manuscripts and often some quite heavy editing in later editions (especially radical in the case of Gollum's story). There are a number of curious inconsistencies (one obvious example being the month that Bilbo set out from Bag End) and it can be fascinating to track them down.
                    - Mark Fisher, personal correspondence

J.R.R. Tolkien's book The Hobbit was first published in 1937, followed by the three books of The Lord of the Rings in 1954, 1955, and 1956. Though Tolkien died in 1973, he was still making revisions to these works in subsequent editions as late as 1965, vainly attempting to correct errors and conflicts that either he found or that others had brought to his attention. Yet many remain, compounded by the many publishers that have issued the various reprint editions over the years. New errors have frequently been introduced, generally by sloppy and/or misguided editing.

There still remain a number of canonical errors in The Hobbit and The Lord of the Rings, original errors made by Tolkien that he never rectified and which publishers are now afraid to correct since they fear incurring the wrath of the Tolkien Estate, which holds practically his every written word to be sacrosanct. A good example of such is to be found on page 150 in The Two Towers, when Gimli saves Eomer's life by beheading two orcs just prior to the battle of Helm's Deep, stating afterwards that he had 'hewn naught but wood since Moria', completely ignoring the battle in which Boromir was killed and in which Gimli and Legolas had together slain dozens of marauding orcs.

Comments below are derived from the boxed paperback set of The Hobbit (TH), and the three volumes that comprise The Lord of the Rings (LOTR), these being The Fellowship of the Ring (FOTR), The Two Towers (TTT), and The Return of the King (ROTK), published in 2014 by Del Rey (TH) and Ballantine (LOTR). Earlier editions of LOTR may be rife with errors. I had begun this exercise with the 1994 edition, finding many dozens of issues, and was then advised that the 50th anniversary edition of 2004 had allegedly corrected many of these. In their introductions to the four books in the 2014 edition, the publishers acknowledge correction of existing errors (the errors previously identified herein by others have indeed been corrected), but, as shall be seen following, that is merely wishful thinking.

The Hobbit is written in a curious mix of first-person and third-person, and includes numerous modern references in Tolkien's first-person narrative, some of which seem to have spilled over into the third-person narrative.

The Hobbit, first written by Tolkien as a story for his own children, was never successfully reconciled with his later masterwork, LOTR, and there remain numerous and significant conflicts and inconsistencies between the two.

Page 20 - the reader is referred to a color map at the beginning of the book, but the 2014 edition being reviewed is in all black-and-white. The original 1937 edition was printed in color, as were some subsequent reprints.

Page 29 - Bilbo complains about 'washing up for fourteen', but, including himself, there were fifteen for which to wash up.

Page 51 - It is stated, "The master of the house was an elf-friend". The housemaster in question was the 6,500 year-old Elrond Halfelven, one of the greatest elves in Middle-earth, and not just a mere elf-friend, as were Bilbo and later Frodo. The title of 'elf-friend' was traditionally granted by the Elves to their allies among mortals.

Page 138 - Gandalf, in reply to Bilbo's asking about an alternate way through Mirkwood, states, "There is, if you care to go two hundred miles or so out of your way north, and twice that south". Gandalf is correct about the distance north, but far off the mark concerning the distance south, since the Lonely Mountain was located near the northeast corner of Mirkwood, according to the map found near the front of the book. Indeed, had Thorin's party followed this alternate route, they would not have traveled much further than they would have by following their original planned route.

Page 150 - it is stated, "...since they started their journey that May morning long ago", but it is clear that prior to this passage the journey began at the end of April. For example, on page 25, Gandalf states, "...your father went away on the twenty-first of April, a hundred years ago last Thursday". Thus it could be no later than April 29 when the journey began the next day. Indeed, on page 12 of FOTR, Tolkien writes of Bilbo, "With them he set out, to his own lasting astonishment, on a morning in April". See Mark Fisher reference in the Foreword.

Page 205-206 - it is stated, "...he and the dwarves found traces of a narrow track, often lost, often rediscovered..." The track (to the secret door) might have often been lost, but if it was only 'often rediscovered' that would mean that sometimes it was never rediscovered, which would mean that they would never reach the end of it.

Page 209 - it is stated, "...and there pale and faint was a thin new moon above the rim of Earth". 'Earth' should either be 'Middle-earth' or 'earth' (uncapitalized).

Page 218 - it is stated, "Get inside Mr Baggins and Balin, and you two Fili and Kili". The word 'two' should be 'too' for this sentence to make sense, even taking into account British English spelling and grammar and Tolkien's many and varied colloquialisms and frequent use of slang.

Page 299 - it is stated, "...Gandalf had been to a great council of the white wizards...". As learned later when Tolkien fleshed out the mythos of Middle-earth for LOTR, there had only ever been five wizards in Middle-earth and only one of them (Saruman) was a white wizard. Thus there could not have been any council of white wizards. In LOTR, Gandalf states that this event was a Council of the Wise (which included elves). Further confusing the issue is the fact that the Council of the Wise was also known as the White Council.

The forest of Mirkwood was about 200 miles wide and, though no definitive timetable is given in TH, it seems to have taken Thorin's party several weeks to cross. They carried all of their own food, water, and other supplies and no drinking water was available within Mirkwood. That said, with a minimum consumption of 1/2 gallon/person/day in summer, each member of the party would have had to carry at least 7 gallons, or 60 pounds of water, this for just a two-week expedition. The mass of this much water alone would approach Bilbo's own body weight, an impossible burden for a hobbit carrying other loads. Though in LOTR we learn that 'dwarves make light of burdens', they obviously carried all that they could crossing Mirkwood or they would not have run out of both food and water as they did. Indeed, on page 137 Thorin expresses his concern that their food may not last, and on page 142 are found statements that both their food and water were running low. It is to be concluded that Tolkien made a probable logic error in this regard.

Page 35 - It is stated, "What the 'ell William was a-thinkin'". The term 'ell is of course cockney English for 'hell', a word and concept found nowhere else in TH or LOTR.

Page 296 - it is stated, concerning Beorn's descendants, "In their day the last goblins were hunted from the Misty Mountains...". If this were true, then neither Balin's company nor the Fellowship should have encountered any orcs while in Moria as described in FOTR. Note that 'in their day', which would have been about 50 years after the events chronicled in TH, would have encompassed the time frame in which Balin's party first entered Moria.

Trolls with first and last names are unique to TH and are not to be found in LOTR. Tom, Bert, and William speak in cockney English, but page 458 of Appendix F in ROTK states that trolls, if they spoke at all (this in the time frame of TH), used only a debased form of the Common Speech.

Goblins are mentioned frequently throughout TH, and orcs rarely, but this situation is reversed in LOTR. On page 38, goblins, hobgoblins, and orcs are mentioned in the same sentence, giving the impression that all three are distinct and separate entities. Tolkien later revealed that hobgoblins were a small breed of goblin, and that orcs were a large breed of goblin (as stated on page 88). Further confusing the issue is the Great Goblin, who, by Tolkien's own criteria, should have been called an orc of some nature.

Page 79 - it is stated that Bilbo had lost his knife "some time ago", but the only 'knife' ever mentioned as being in his possession was Sting. Yet on page 80 he fends off Gollum with his "little sword", which is what his elven 'knife' Sting actually was. Since, as Tolkien tells us repeatedly, Bilbo left on this adventure without taking a handkerchief, hat, or any money, it is really doubtful that he would have taken a knife with him. If the dwarves gave him a knife, as they did a hood and cloak, Tolkien never mentions it.

Page 169 - it is stated, concerning the Wood-elves, "The giant spiders were the only living things that they had no mercy upon". Yet, on page 283, it is stated, again concerning the Wood-elves, "Their hatred for the goblins is cold and bitter". On page 292, concerning the goblins, it is stated that all goblins within the Wood-elves' realm were either slain or drawn into Mirkwood by the Wood-elves to die a presumably lingering death. These acts on the Wood-elves' part certainly qualify as 'merciless'.

Sting is described variously as a dagger, a sword, or a knife.

Bilbo's handkerchiefs are identified both as handkerchiefs and as pocket-handkerchiefs.

Throughout TH, the trolls are identified as Tom, Bert, and William, until page 301, where William suddenly becomes Bill.

Mithril terminology use is confusing. Among its variations are listed 'silver-steel' (page 240) and two other terms in LOTR, these being 'Moria-silver' and 'truesilver'. Note that mithril terminology found in TH is not found in LOTR and vice-versa.

Pages 42-43 - the 'pots full of gold coins' are subsequently referred to as 'pots of coins' and 'pots of gold'. On page 301, these pots are called 'the gold of the trolls'.

Page 52 - Glamdring is described as 'Foehammer', but in all other instances it is referred to as 'Foe-hammer'.

Page 112 - 'the battle of Five Armies' is referred to in all other instances as 'the Battle of Five Armies' (capitalized).

Page 10 - Gandalf mentions a 'pop-gun', which obviously did not exist in Middle-earth.

Pages 24 and 226 - mention is made of a 'hurricane', which could hardly be known in Middle-earth.

On pages 395-397 of Appendix A in ROTK, we learn that the whole story of TH was just a ploy by Gandalf to eliminate Smaug, thus preventing Sauron from allying with him in a future war against the West that was foreseen by Gandalf. If not for Bilbo and his ring, the dwarves would never have reached the Lonely Mountain at all, and Gandalf's ploy would then have merely sent them all to their deaths in Mirkwood. Even then, the only contribution that Bilbo made to the destruction of Smaug (the dwarves did nothing other than to gain access through the secret door) was to observe that Smaug had a vulnerable patch on his breast, the exploitation of which would be left entirely to the men of Lake-town, Bard in particular, and Bard's success was, both literally and figuratively, a long shot. How Gandalf thought the venture of Thorin's party as he had planned it was going to succeed is a mystery, as its success depended entirely on Bilbo finding and using the One Ring repeatedly, events that Gandalf could not possibly have foreseen.

What became of the dwarves' musical instruments they brought to Bilbo's house?

Why would the trolls have locked the entrance to their cave at night, when the key could be (and was) easily lost and being locked out would mean their deaths come daybreak? Locking it instead during the daylight hours, when they would presumably be inside sleeping, makes perfect sense.

Gandalf had been in Middle-earth for around 2,000 years up to this point but had never had a sword until he found Glamdring in the trolls' hoard?

Who or what exactly was Beorn?

Since both Gandalf and Beorn obviously knew of the giant spiders in Mirkwood, why did they not just come out directly and warn Thorin's party about them? Gandalf later showed the exact same negligence in LOTR by not warning the Fellowship about Shelob, as there were only two viable entrances into Mordor, one of which ran through Shelob's lair.

What did Smaug normally eat, as the dwarves observed there was nothing edible to be found within the Desolation of the Dragon, and Smaug had not been preying on Lake-town?

Why was the elvenking never identified by name (Thranduil) until LOTR?

Where was Legolas all this time? The son of the elvenking, he is never mentioned until LOTR although he was by then several thousand years old and undoubtedly around Bilbo and the dwarves during their time in his father's realm.

Page 25 - Gandalf relates how he came by the map of the secret door and its key. Yet on page 395 of TTT, there is detailed discussion as to how thoroughly Sauron's prisoners were searched, with all that was found being confiscated. How could Thrain possibly have retained possession of these two items while a prisoner of the Necromancer (Sauron), when the great ring he possessed was found and confiscated?

Page 132 - Beorn states, "I will provide you with skins for carrying water". However, on page 116 Gandalf states of Beorn that he does not eat his cattle and horses, nor does he hunt and eat wild animals. That said, where then did Beorn's water skins come from? Why then did he also have bows and arrows, and why did he have enough of them to outfit 13 dwarves?

Page 232 - How did Thror and Thrain manage to escape through the secret door in the first place if there was no keyhole on the inside when the door was closed?

Page 293 - With portage weight and volume at a premium on the long trek home, why did Bilbo select a small chest each of gold and silver as his share of the dwarves' recovered treasure, when silver was worth so much less than gold? Two chests of gold and none of silver would have made much more sense given the circumstances.

To be continued...