Continuity mistake: Before the cop climbs on the truck, he shields himself on the truck's cabin and you can easily notice the tarp is perfectly tied by a dozen strings. When he climbs up, all the knots magically untie and he manages to pull the tarp away. His buddy couldn't have done it because he always appears with the gun in his hand, covering him.
Picture added by Sacha
To submit a picture, just click the edit icon under the relevant entry, then choose 'add a picture'. Thanks!
All images remain the copyright of their original owners - these low resolution images are simply individual frames used to demonstrate the entry.