Factual error: It is stated that Miss Trunchbull competed in the Olympics in shot put, javelin, and hammer throw. According to her jersey those were the 1972 Olympics. The hammer throw wasn't added as an Olympic event for women until 2000.
Factual error: When Howard is running after the bouncy ball he is on the second floor of the Mall of America, however, you see him run through the LEGO store which is located on the lowest floor of the Mall of America, which is impossible if he was on the second floor before.
Factual error: When the plane is taking off while the animals are on the runway they duck down hoping it will stop and it becomes airborne shortly before hitting them. In actuality they should have been blown backwards from the jets like ragdolls.
Factual error: Towards the end of the song "Out There" Quasimodo climbs onto the large spire on the roof. That spire was added in the 19th century and thus didn't exist when the movie was set.
Factual error: Throughout the entire Varsity/JV game, the Varsity team makes at least 20 penalties that aren't called. They also refer to a tripping call as hooking, even though the Varsity player obviously goes for the JV players ankles.
Factual error: At the start of the movie Amy and her mother Alaine are in a car accident near Auckland, New Zealand. The ambulance is a US or Canadian ambulance, as New Zealand ambulances do not have the word paramedic on the side.