Other mistake: The hole that the guy got his arm torn off in was too small to fit into, despite the monster being on the other side. A few moments later, he's pulled in. If the opening was too small, the body would be crushed and blood would spray everywhere, but you see none.
Graveyard Shift (1990)
Ending / spoiler
Directed by: Ralph S. Singleton
Starring: Andrew Divoff, David Andrews, Stephen Macht, Kelly Wolf
Genres: Horror
The monster is really a huge bat who has stacked tons of human remains in an underground cave. Everyone dies except the drifter.
Nikki Williams
More mistakes in Graveyard Shift
[John Hall readies a can to shoot at the switch for the machinery to kill the monster.]
John Hall: Way to deal with these fuckers!