When Irene is introduced to Lake Consequence and she is on the pier, Billy pulls the pier in by a rope which wasn't there in any previous shot.
When Billy is attempting to wrestle Irene to the ground on the grassy area, both Billy Zane and Joan Severance morph noticeably into different people (i.e. their stunt-doubles) in a few shots and lasting considerable seconds.
At 8 minutes: when Irene is tracking Billy's movements in her car's mirror, neither the camera nor the mirror move to allow this, so this is a composite picture.
After Irene set the fire in the bathhouse, the camera showed Irene running out of the bathhouse almost half-naked and barefoot. The story continued with Irene putting on a man's oversized jacket to cover her nakedness in Billy's truck. When Irene ran away from Billy's truck, she was wearing a pair of woman-sized boots with shoelaces nicely tied which allowed her later to run on the grassy area.