Other mistake: Murphy lands the helicopter on a railway line so an oncoming train will destroy it completely, and this happens exactly on cue with huge, dramatic explosions and flying debris. Apparently the train driver doesn't think this is important enough to interrupt his busy schedule - he doesn't stop the train. We do not hear brakes being applied - the wheels would make a noise like the sky coming down - and the train doesn't slow down at all - it just keeps on going.
Other mistake: In the scene that begins with "Three Months Later" where Tony and Manny are sitting at the table near the beach watching the girls in bikinis walk by, Manny is attempting to explain to Tony how to pick up women by explaining what "women in this country know and understand". After Manny sticks his tongue out to demonstrate and Tony asks Manny "what the f*ck was that, Mayne?", if you watch Al Pacino's lips as Steven Bauer is talking, you can see Al's lips moving in unison to whatever Steven is saying.
Other mistake: When Harry gets to his vacation spot he is greeted by a dog. A few seconds later the dog is seen lifting his leg to pee, showing his dog is a male. Later on in the film after he returns home after the main killer has killed the second victim, the dog is scratching at the door. If you pause the movie at this moment you notice the dog has a sagging belly with nipples just like a female dog after delivering puppies. (00:48:05 - 00:57:20)
Other mistake: During the police chase, Mick hits Paco's little brother and then slams into the white van, and it instantly bursts into flames creating an inferno. Which would not occur under normal circumstances. But merely dramatized for movie effect.
Other mistake: When McQuade is leaving his house in his truck to head to Mexico, he is wearing a light beige button-down. When we see the shot of him in his truck pulling away after Kayo is yelling "You're in no shape to do this alone!", his shirt changes color to light yellow. It's also light yellow for the remainder of the scene at the gas station/restaurant.
Other mistake: As Buford takes off from the tow truck, a brown piece of metal is seen where there shouldn't be one. Probably for a later stunt.