Plot hole: When Farley is preparing to rescue Simon by towing him up with the rope attached to his van, he drops his "cigarette" into his crotch, causing him to floor the gas pedal. His back wheels begin to spin. This is impossible because the vehicle is still in Park. There is even a camera shot of the "PRNDL" proving this. I guess this goof is employed by the filmmaker to increase the dramatic effect of him subsequently slamming the Dodge into drive a second later and careening through the fence.
Continuity mistake: When Farley drives through the fence after tying the rope to the front bumper of his van, the rope remains tied until the head on shot of him looking terrified traveling straight down crashing toward his buddy, Simon, when the rope disappears. Magically, it returns (still tied to the vehicle's front) a 10th of a second later in the following side shot of the van, right before crushing poor Simon.