The Devil BatGoofs

Although all the bat attacks occur at night, much of the footage of the bat flying to and from its destinations was clearly shot in the daytime.

At 8:30, when the doctor is in the lab "feeding" the bat the fragrance, the bat's head and body are all black. In the stock footage cutaway to the closeup of the bat, the bat's body is white.

When the reporter wrestles the doctor to the ground near the end of the film, their feet clearly wrinkle the fake grass on the set.

After Johnny Layton (Dave O'Brien) shoots and kills one of the devil bats, the article in the Chicago Register states his name as Henry Layton, while another one in the Springfield daily correctly names him as Johnny.

In the lab scene, when Tommy tries to flick a drop of the deadly lotion on Dr. Carruthers, he flinches away and says he has a violent dislike of perfumes. Immediately afterward though he shakes Tommy's hand which has been slathered in the lotion.

Throughout the movie, references are made to Illinois locations (Chicago, Peoria, Springfield), yet the scenery shown at the beginning of the movie is clearly Californian.