This goof is toward the end of Terry's eye surgery. Look closely at the sheet that is covering the lower part of his face. From the beginning of the operating room scene, the sheet is lying smoothly over Terry's nose and mouth, with no creases in it. However, when the dialogue gets to the part where Terry says "hold it....let the nurse do it", the sheet now has several creases in it. When Terry asks the nurse her name, the sheet is once again lying smoothly over the lower part of his face.
This is when Terry and Lynn are in Terry's car going on their picnic. Lynn noticed the suspects' green van following them by looking in the rear-view mirror...only, there is no mirror in the car. It should be noted that she didn't look in either the left or right side-view mirrors, she specifically looked up where the rear-view mirror would normally be.
Disappearing necklace? Look closely at Terry's neck when he and Lynn are running down the hill to the plant. Terry is wearing a necklace. In the part where he's waiting for Buzz to come down the stairs, Terry's shirt is still open at his neck, but the necklace has disappeared. It's very clear that it isn't there. Somehow, it manages to reappear when he meets up with Mike and Willie just before they leave.