The famous rock climbing sequence was filmed at Dead Horse Point in Utah. Tom Cruise was on cables which were then digitally removed. Ron Kauk was the climbing double and the overhang stunt was performed by main stunt double Keith Campbell. Director John Woo was so scared each time but "Tom insisted on doing it".
Tom Cruise and John Woo clashed over some of the stunts as Woo wanted stunt doubles, and Cruise was adamant about doing them. He told Woo he didn't like "cheating" and that it's too easy to spot when the actor is being doubled because of body movement, timing, et cetera. It didn't help that Woo is afraid of heights. Woo admired Cruise's courage.
Dougray Scott (Ambrose) was going to play Logan/Wolverine in X-Men (2000). When filming went over schedule and he was injured in a motorbike accident, he was forced to drop out and was replaced by Hugh Jackman.
Director John Woo's first cut of this movie clocked in at three and a half hours. Paramount Pictures balked at this length, and told him that the final length could not exceed two hours. This would explain why there are so many plot holes and continuity errors in the theatrical cut.
Tom Cruise's then-wife Nicole Kidman suggested Thandiwe Newton (Kidman's co-star in Flirting (1991)) as the love interest for Ethan Hunt. She was cast before the script was written.