When Mr. Bodi's corpse falls down, he is shown to have been decapitated, but in the next shot of his corpse lying down, his head is completely attached.
After Damon runs over the alien at the gas station, a little bit of blood splatters all over a billboard. A couple of shots later, however, more blood than previously seen is all over the billboard without any explanation as to how it got there.
Baby Bodi's tricycle changes between shots of Mr. Bodi's corpse falling down.
The American flags on the shoulders of the pressure suits worn by the NASA operatives have only 49 Stars.
Parts of Skylab in real life, had actually fallen somewhere in Australia, but this is never addressed at any point in the film.
Obvious dummy when Dr. Tracer is ran over by the truck.