The production asked the Czech Air Force for the loan of two of their jets for the film, only to be told that they could have the entire fleet. All that was required as payment was a $50,000 donation to a pilots' hospital, and to buy beer for all the soldiers involved.
Stunt player Harry O'Connor was killed when he hit a pillar of the Palacky Bridge in Prague, para-sailing during one of the actions scenes. The accident occured while filming the second take of the stunt; O'Connor's first attempt was completed without incident and can be seen in the completed film.
In the action scene on the drug farm, Vin Diesel and/or his stunt driver were wearing bulky helmets, which were replaced with a CGI version of Diesel's head, created by the people at Digital Domain, who also repainted parts of the clothing which were obscured by the helmet(s).
When the smoking sniper pins down the officers, the rocket launcher Xander uses is actually a modified video camera painted green.
In the DVD extras, Vin Diesel comments that before his three month preparation for this movie, he'd never ridden a motocross bike. He was trained by the world's top motocross bikers.
Tony Hawk: One of the crew who collects Xander after the bridge BASE jump, driving the getaway car and telling two others to grab the cameras from the crashed Corvette, is pro skateboarder Tony Hawk.
Rich Wilkes: As Xander proclaims "I'm untouchable" to JJ, the writer of xXx, Rich Wilkes, is seen behind Xander. He is the tall man with the white blonde hair and blue shirt.
Thomas Ian Griffith: as Agent Jim McGrath, the Bond lookalike who gets killed in the opening concert scene. Griffith had previously played both heroes and villains in several B action films in the 90's.
Rob Cohen: as the horse-riding Colombian, and later as the voice of the telephone caller who informs Yorgi that xXx is a spy.