Revealing mistake: When Lewis gets out of the tub and has a towel around him, you can see he has underwear on.
Continuity mistake: When Louis enters his garage, he leans his rake against the wall. When Church the cat runs out, the angle of the rake is different.
Other mistake: In the beginning of the scene where Gage is killed by the Orinco truck, the truck leaves the plant. The number on the trailer is marked T-80. In the scene, the truck rolls over in the accident. In later scenes where Rachel hitches a ride home with another Orinco truck, the number on the trailer is also marked T-80.
Revealing mistake: When Louis goes to give Gage the shot if you look closely you can see that the needle doesn't leave a puncture mark.