In the scene of the downtown street where Steve looks around to see where the "PURLE" car went, the shops and other scenery change drastically between shots, and the parked vehicles appear and disappear as Steve drives slowly up the street.
Squarish grid-pattern of the burned special-effect flash-cord easily visible on the chain-link fence.
When Steve goes to the doc's house the second time, the house and bushes are brightly lit, yet the sky is black; obviously a movie-light illuminated scene filmed after dark.
Obvious imitation-metal "dull-leather shine" finish and flexible-material bending action on the hard-rubber gun that Steve crushes in his hand.
Steve's driver's licence has Washington misspelt as Washungton.