The Hogwarts' equipment list mentions the Lockhart book "Wanderings With Werewolves," but later, Lockhart refers to the book as "Weekend With a Werewolf." (Fixed in later editions).
The cover illustration of Harry, Ron and Hedwig in the flying Ford Anglia incorrectly depicts Hedwig as a Barn Owl rather than a Snowy Owl.
When Harry and Ron arrive at Hogwarts in their father's flying Ford Anglia (a scene which takes place on 1 September 1992), they are told that they had been seen by Muggles in various situations, including flying past the "Post Office Tower." Quite apart from the fact that a change of ownership means that the building in question has been called the "BT Tower" since 1984, said building is about a mile south-west of King's Cross, so to be passing it, Harry and Ron had to be going in entirely the wrong direction to be following the Hogwarts Express, or even the tracks generally.
After Harry, Ron, Fred, and George arrive at the Burrow after getting Harry, Mrs. Weasley shouts at Fred first. "You will not," then she says, "And you two," glaring at Ron and Fred. It should say George, as she has already yelled at Fred. (Fixed in later editions.)
Dumbledore tells Harry at the end that Lord Voldemort is the last remaining ancestor of Salazar Slytherin. But ancestors are in the past — he means Voldemort is the last descendant of Salazar Slytherin (Corrected in later printings).
Hermione says Moaning Myrtle haunts the bathroom on the first floor. However, when Harry sees the writing on the wall outside her bathroom, he is on the second floor. This is explained by the fact that in the UK, the ground floor is the floor on which the entrances are, and the floor above it is the first floor, and this was one of the few edits made for the North American release, despite the criticism on edits for Philosopher's Stone.
When Harry is viewing the memory from Tom Riddle's diary, Tom Riddle says to Hagrid at one point, "The dead girl's parents will be here tomorrow." It is stated elsewhere in the book that Myrtle is Muggle-born. Muggles cannot enter Hogwarts. It is possible, however, that an exception was made for them; that the Muggle-Repelling Charm could be lifted a day or two, for this reason. Considering that the Grangers were able to enter Diagon Alley without any problems when normal Muggles could not see The Leaky Cauldron, this theory is somewhat strengthened.
14th February 1993 is Sunday in the real world, yet in the book the students had their classes on that day as Harry got his 'musical message' when he walking upstairs for Charms.
When Harry speaks Parseltongue to the snake during his duel with Draco, everyone hears him hissing. Therefore, when Harry hears the basilisk speaking in the walls, Ron and Hermione should hear hissing, yet they claim to hear nothing. They might, however, hear pipes hissing but subconsciously ignore it, dismissing it as creaking wood, an air current going through the pipes, or other animals such as mice. Alternatively, it could be that the snake is simply making a very quiet hissing. The basilisk's voice is implied to be a whisper and Harry, being the only one to hear English words, would be the only one to notice anything.
The first day of term is always the 1st September, the next day is always a Monday. This is impossible, due to the fact that the year does not have 364 (divisible by 7) days.
On page 283 of some copies of the U.S. paperback edition, the word professor is spelled as professorr.
Percy's name is spelled Perry (Fixed in later editions).
