Continuity: In the bowling scene, the pins in the lane to the left of the one that "Ug" (disguised as "Johnny Steele") uses disappears in the last shot of the scene.
Continuity: Helen Brown drops a plate she is cleaning, and it smashes on the floor; she runs to the window to look outside, when she steps back, part of the smashed plate is on the counter.
Revealing mistakes: During the scene where Lee transforms into the body of Reverend Miller, Jeremy Lawrence is obviously replaced by another actor at the podium.
Continuity: The Bounty Hunters leave Earth at the end of the film in a different spaceship to the one they arrive in. In fact, it is the same model used for the ship the Critters arrived (and attempted to leave) in.