Near the beginning of the film, a mercenary team is moving through the jungle. One of the men starts to mess with a piece of his equipment when another tells him not to bother as their GPS equipment won't work where they're at. Since GPS uses satellites, their equipment will, in fact, work anywhere in the world as long as they're outside.
When Payu, Long Fei and Xian hide in the restaurant, they climb up the air vent above the stove and stay there. The air vent and the pipes up there would be extremely dirty but when they come down, their clothes look like before (especially noticeable on Xian's white pantsuit).
When Xian was about to go to the Chinese embassy, she was stuck in traffic, then borrowed Payu's cellphone to call her female police guard. Strangely, the police could immediately find out that Xian was the one who contacted her, even though Xian called with Payu's cellphone.
During the final confrontation, Collins asks the the rivals to bring the girl over to a place and promises they will give $100,000/- in exchange. They do so. But Collins or one of his henchmen could have easily put a bullet in to the girl at that time as the rival group do not hold any security over Collins or the group.
An attack with automatic weapons and explosions is not an every day event, even for police officers. Yet, during the entire attack on the police station, not one officer gets the idea to use a phone to call for backup.