 CONT: In the first test run scene, Doc insists they wear radiation  suits, because of the tube of plutonium. However, when he says Safe  now and places the empty plutonium holder back in the case, both  Marty and Doc Brown remove their protection and Doc opens the case  containing 14 other tubes of plutonium!!!  During the first experiment where Marty first sees the DeLorean, the  ramps on Doc Browns van lower. In the first shot, the ramps have wet  tire marks as if the car has just been driven into the back of the  van from the wet parking lot, but on the next shot of the ramps  coming down, they have been wiped clean of tread marks.