When the rear engine Corvair with the trunk in the front stops behind the truck, Barney opens the trunk, climbs onto the back of the truck, and the Corvair trunk lid appears to close all by itself, which is impossible, so someone must have been hidden inside out of camera range to pull it closed.
If you look closely at Barney's a "lock pick" when he breaks into the truck, it's really an actual key on a lock pick handle.
The Spanish word "REPARACIONES" is misspelled "REPARACIÓNES".
A sign for California SR-14 is seen along with a Mexican stop sign (Alto). SR-14 does not extend to Mexico.
It is not shown or explained how the IMF team substitutes the peanut cans for the drug pills cans.
When Barney sneaks onto the truck carrying the drugs, he tells Jim there are ten cases of them. However, in some shots there are at least 19 cases.