In the opening scene, the sunlight changes drastically and constantly between shots; initially it's golden on the horizon; then alternates between high mid-afternoon sun with blue sky, to gray overcast sky with no shadows.
In the parking lot scene near the beginning of the movie several cars have the third brake light which wasn't mandatory until mid eighties.
In the first scene, while Rodney is photographing Sarah the image in the viewfinder zooms back and forth as he composes a shot. However, the camera he is using does not have a zoom lens.
Near the end of the film, her name is spelled Cheryl on one of narratives that reveal what happened after the film. Her name is actually spelled Sheryl, which was correct in the cast list.
The flowers on the walls of The Dating Game set are incorrectly formed out of unconnected heart-shaped petals. The original ones were large abstract/mod flowers with all the petals joined together at the center.
The coins stolen from the laundromat are modern day quarters. Not 1979 or earlier. 3 different Washington heads can be seen. These would be national park quarters and later minting.
When Laura and her boyfriend walk in the parking lot toward the studio when can see in the background a cellular tower. Cellular telephony was not available in the 70s.
When Sheryl is running from the laundry with a large man chasing her, a 1985 Chevrolet Chevy Van can be seen to the right, 7 years out of the date for the movie's 1978 setting.