When the "cat" attacks a truck driver, the truck changes models in the crash footage.
Size of the cat mutant varies wildly in different scenes (gets larger, then smaller, then larger again) throughout the movie.
Lance is shot at in front of a large glass window, and his arm is grazed by the bullet. However, the window behind him is not broken.
Lance's bandage is soaked in the blood, despite the fact his arm was only grazed.
When the cat attacks the driver of the red pickup truck the puppeteer's arm is visible.
The boat seen during the "storm at sea" sequences is very clearly a toy model. A wire can briefly be seen pulling it down as it 'sinks.'
The cat meows throughout its voyage on the ship but its mouth never moves.