Revealing mistake: At the end of the movie, the main creature has the head of a human. However, in a number of shots you can see the actor's neck showing how they made the head "appear" to be attached to this creature.
From Beyond (1986)
1 mistake
Directed by: Stuart Gordon
Starring: Jeffrey Combs, Ken Foree, Barbara Crampton, Ted Sorel
Buford 'Bubba' Brownlee: All this talking about eating is making me hungry.