Corrected entry: At Fort Benning in New Mexico when Christian Bale is given his assignment he is told President Harrison gave it. Harrison was president in 1841, but later Tommy talks about his first kill when he was 14 - he fought with the Greys or Confederacy which wasn't until the 1860s.
Corrected entry: When Caesar tries to throw the grenade, he takes out the pin, then he gets the arrow in his chest. The grenade touches the ground but doesn't explode, he takes it again and throws it at the fuel tank, and now it does explode.
Correction: The grenade that he threw isn't an impact grenade and wouldn't go off just because it hit the ground. And pulling the pin doesn't activate the detonator either. Once the striker lever is released the percussion cap is struck, activating a chemical delay (or fuse). The delay on average is 2-6 seconds, but it could be longer depending on how it was made.
Corrected entry: There is a scene where Voldemort uses a Levitation Charm ("Wingardium Leviosa") on Batman, but in the canon of Harry Potter, this spell does not work on human beings.
Correction: Unfortunately, this is not meant to be part of the Harry Potter canon, as just about every Batman canon is ignored in this movie and broken whenever possible. Any discrepancies are invalid. And, as a die-hard fan of Harry Potter, there is never any film or book evidence that "Wingardium Leviosa" works on humans.
Corrected entry: It's unbelievable that Trini survived when she fell from the top of the cliff.
Correction: She fell into water. The height of the fall is never shown so we can't really speculate how far down it was, but it's very reasonable that the water broke her fall without hurting her.
Correction: There were 2 President Harrisons - William Henry Harrison, president in 1841, and his grandson Benjamin Harrison, president from 1889-1893.