The headrests in Chon and Ben's Jeep disappear are reappear several times depending on the scene. They are missing when Dennis the DEA agent gets in to talk with them. Later in the desert ambush scene, they have been replaced.
During the scene when O is e-mailing her mother about Paris (while she is really being held captive) we first see the headphone remote/volume control knob on her right, but in the next scene it is on her left.
When the cartel 'motorcycle cop' comes up to the guy's car, after pulling him over, he has his hand on his holstered pistol. The pistol does not protrude through the bottom (barrel) - standard issue type. But, when the hit-man shoots the guy, there's a silencer on the barrel. There was no time to have screwed one on. However the hit-man has a holstered pistol on his right hip; he grabs the weapon that he uses to kill Frankie with his left hand from the back of his body.