Continuity mistake: When Alice knocks over the giant Licker in the Rolls-Royce, the driver's side of the car remains completely undamaged. Unlikely, but for the rest of the chase there are four giant scratches across the rear of the car. (00:51:10 - 00:52:05)
Continuity mistake: Outside of the corridor of light sequence, nobody ever seems to run out of ammo, or bother to reload, most notably Ada and Alice.
Continuity mistake: When Jill Valentine jumps out of the Umbrella chopper, her outfit and guns differ from what she was wearing and carrying in the post-credits scene of Resident Evil: Afterlife. (00:05:55)
Factual error: Semi-automatic guns don't just click empty, like they do in a lot of movies. The slide would lock back until you manually cock the gun. Yet in the corridor of light scene, this is exactly what happens: Alice's gun just clicks when it's empty.
Continuity mistake: In the scene when Ada Wong walks into the Umbrella control room and kills all the agents, she stands in the middle of the room. She uses a gun to kill all the agents, who are sitting behind glass computers. In that scene, and in later shots, we can see that the glass is intact and has no bullet holes in it.
Factual error: Alice and Ada blow up a taxi by shooting the gas-tank. Shooting the gas tank of a car won't blow it up - as was tested by Mythbusters. (00:38:15)
Continuity mistake: The Rolls-Royce constantly goes from being bulletproof, to not being armored at all.
Continuity mistake: When Alice is being chased in the corridor of the Tokyo simulation, the woman in the blue dress is a good distance away from her. However in the following shots she is much closer. (00:21:15)
Continuity mistake: Ada Wong seems to never run out of ammo. She never reloads and she doesn't carry any magazines with her. Alice's Kriss Vectors should only hold 13-33 rounds but she fires more than the rounds. She doesn't hold any mags.
Continuity mistake: During the fight in the corridor of light, Alice shots everybody and there are a lot of blood splattering, but the corridor continues to be clean until the very end, and the stains of blood that are there are not compatible with the splatters. (00:21:50)
Revealing mistake: When Alice shoots the zombie in the blue dress, we get a frontal shot of the gun. Pay close attention to her trigger finger: it doesn't move at all, while the gun does fire.
Other mistake: When Alice pushes in the new magazine, she doesn't pull back on the slide, meaning the gun doesn't have a new bullet in the chamber, thus is unable to shoot.
Factual error: Rain injects herself with the Las Plagas parasite, which seems to take the form of a little scorpion. Little or not, it's not small enough to be pushed through an injection needle.
Revealing mistake: When Ada Wong kills three officers in the Umbrella Central Control Room, you can see she shot them from the front. They are sitting behind glass panels. Later, we can see the blood splatter sitting on their side of the glass, indicating that they were shot from behind. The glass is also intact, despite a bullet supposedly passing through it. (00:27:30)
Continuity mistake: When housewife Alice is trying to escape with her daughter in the laundry room, she slams a mop through the ceiling. When she slams the mophead through the ceiling the last time and pulls it out, the hole left behind is maybe one foot across. When she lifts her daughter up into the hole it is now a good two or three feet across and reaches from ceiling support beam to support beam. (00:09:20)
Deliberate mistake: Empty magazines aren't that heavy, but when Alice kicks it into the face of one of the zombies, it looks like he's being hit with a baseball bat. (00:22:45)
Continuity mistake: One of the zombies fires an RPG into a yellow van. The van then moves forward and bumps into another car in front of it. When Alice jumps through the van, they have moved apart again. (00:50:45)
Factual error: Typhoon-class submarines have a crew of 163 men. It is impossible for Jill Valentine to operate a submarine on her own, even with help from Rain.
Revealing mistake: Alice throws a new magazine for her gun up, and it stays in the air for a good ten seconds (adjusted for slow-mo). For something to stay up in the air, you would need to throw it a good hundred feet, and the hallway simply isn't that high. (00:22:40)
Other mistake: Alice and Ada blow up the NY Taxi in a huge fireball but don't get effected by the fireball despite being only 3-4 foot away from it. (00:36:40)
Chosen answer: Jill was unconscious at the time, while Claire was awake, therefore the loss of memory may differ by state of mind, or vary from person to person.