The surveillance tape shows Tom Hanson turning around and calling out to Amy, before she calls him and drops the bottle of ketchup; but when it is actually shown what happens Tom Hanson calls out to Amy after the bottle is smashed.
Before the opening credits, the scene in the convenience store plays out with Amy calling out "Tom", dropping the jar, then Tom calling out "Amy" and then the gunshot. However, whenever Tom watches the surveillance footage, the video always has him calling out for Amy first.