Other mistake: In the scene where Dr. Isaacs is in the teleconference with the Umbrella Board of Directors, there are several glasses of water sitting in front of each individual hologram. At the end of the teleconference, the holograms of the board members disappear, but none of the glasses follow suit. This tells us that the glasses of water were physically in the room with Dr. Isaacs, for absolutely no reason, given all the other attendees weren't really there. (00:17:40)
Other mistake: As Chase pulls the tanker to a stop in Vegas, the engine revs once more before it's shut down, but the rain caps don't pop up as they should from the extra puff of exhaust. (00:54:50)
Other mistake: In the end fight scene between Dr. Isaacs and Alice, she bumps into the water cocoon and awakes one of her clones only to have it die a few seconds later. When she goes to cover up the body, the clone can be seen wearing a wedding ring - they don't incubate the bodies wearing jewelry in an embryonic state.
Other mistake: In order to use the vials that have either the T-virus or the anti-virus it has to be loaded into a special gun-like tool, similar to a caulking gun. A plunger is then set, and released with a trigger, again, like a caulking gun. The problem is that when the vials are seen, the caps on either end are solid, with no hint of an opening for the fluid to get out and into the body that it is being administered to.
Chosen answer: The reason that the cloned alices were put through the tests was their attempt to get a "perfect" clone of her. They knew that Alice was the key to taking back the zombie infestation, so they were trying to get the "perfect" clone. The perfect clone would have all of her memories and reactions, so they put the clones through that testing facility. If she made it out alive, then she was the perfect clone. If she didn't, then it was back to the drawing board.
Nick Bylsma