Visible crew/equipment: When the car crashes and flips at the start of the film, a catapult can be seen swinging under the car as it rolls over. This is what was used to get the rear end of the car airborne. (00:02:55)
Continuity mistake: When the car comes to rest after turning over, there is enough space between it and the wall to drive another car of similar size through. But when we look down on the wreck from the overpass, there's no more than a foot of space. (00:03:00)
Continuity mistake: When a nude Brad Pitt is digging a big hole, at first his skin is clean, then in an instant with a camera angle change he is covered in dirt and sweat.
Answer: Presumably it was to bury the trailer park landlord who Early had murdered.
raywest