Revealing mistake: In the scene where the black guy is using the toilet, when the cat bites his balls and when the cat is latched on to his balls, you can tell it's not a real cat. It is obviously just a stuffed toy.
Revealing mistake: When we see Deuce on the airplane, he's carrying Kate's leg in his bag. Notice how it wobbles like rubber when he hits people in the face. Fake legs are made to support the persons weight and wouldn't wobble in any way.