Visible crew/equipment: After the first Alice clone dies in the movie and Dr. Issacs takes off his helmet, look at the scientist to HIS right(our left) you can see the boom operator in his reflective mask along with the camera operator. (00:04:50)
Plot hole: When the survivors arrive in Las Vegas, all that is visible is the Strip. No other buildings are seen, even though Las Vegas has other high-rise buildings that are not on the Strip, and the level of sand that has built up is not substantial enough to have buried the entire city. (00:55:00)
Continuity mistake: When Claire approaches Alice who is watching Issacs fly away, Claire has her hands behind her back in one shot and up at her face in another. (01:05:00)
Revealing mistake: We see Claire loading her weapon when Mikey is being attacked. However if you watch closely you will see she is loading blanks into the weapon. (01:01:40)
Continuity mistake: Betty gets attacked by the birds and ends up with blood all over her face. When she shuts herself in, the blood is all gone and her face is clear. (00:39:00)
Continuity mistake: When Stevie is shot, there is blood spatter on the truck. When we see the close up of him the blood spatter has gone. (00:19:00)
Revealing mistake: When the blade cuts the trolley in half, the blade hits the top of the trolley but the metal frame of the trolley is to break in a perfect cut. (00:04:30)
Continuity mistake: Alice jumps up to avoid the laser at the very start and the laser cuts part of her dress off that is to fall to the floor. However when she lands the separate part is not on the floor where it should be. (00:03:30)
Factual error: The sign in Vegas has the wrong wording. It says "welcome to the fantastic Las Vegas" instead of "Welcome to the Fabulous Las Vegas". (00:51:10)
Continuity mistake: Carlos dives under his truck and finally shoots the two zombies in the head and his scarf is not around his mouth. As the camera changes, it suddenly is. (00:59:45)
Revealing mistake: When the convoy is on the way to Vegas, tyre marks can be seen in the sand ahead of the convoy possibly from previous takes. (00:51:50)
Continuity mistake: Alice exits from the gas station and gets on her bike to read the book she obtained inside the gas station. However we see her looking at a page with a picture and the word "Isolated" on it. When the camera changes and she is closing the book it's on a different page. She's not changed the page as it's audible when she does and the sound is missing. (00:20:15)
Continuity mistake: When Stevie is against the truck, his head is tilted to his left while impaled. But in the close up of him being impaled his head is looking straight ahead. (00:18:30)
Continuity mistake: When Stevie is impaled on the abandoned truck, he's seen in a strip of shade, when Alice walks over the strip of shade has gone. (00:18:30)
Revealing mistake: When Stevie is looking around in the desert before being shot, you can see the outline of his facial makeup around his eyes. (00:17:50)
Continuity mistake: At the start, the woman falls to the floor and you can see her kneepads under her trousers. (00:04:15)
Revealing mistake: When the woman is attacked by the dogs you can see the protective padding on her arms where the dogs bite her. (00:04:15)
Continuity mistake: At the start, the trolley gets cut in half and Alice isn't stood near either of the two halves. When she starts walking off she's next to part of the trolley. (00:04:10)
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