Continuity mistake: When Dr. Strowski approaches the door to the house in the swamp, the door is a dark color with a circular ornament in the middle and only two panels. When the same door is seen from inside the house (the door opens inward), it is a light color, with five panels and no ornamentation.
Continuity mistake: After Janet has crashed her car in the swamp, you can see a snake in the tree next to her. In long shots, the snake is a light color, and is completely immobile. In close-ups, the snake moves and is a darker color. Also, when Lobo finds Janet, the snake is back to its original position, even though we saw it starting to crawl down the branch it was on.