From what I've read at least two Mosquito B.35 airframes were purposely destroyed during filming. Three went on to be used in the kinda sequel to 633 called "Mosquito Squadron" which was a dreadful film IMHO (it used a fair amount of footage from 633 but other aspects of it were just plain bad and done on the cheap). I think Kermit Weeks' B.35 Mossie was one of 633's stars, but sadly it's not flown in several years. There's another B.35 undergoing restoration in Victoria, British Columbia and an FB.26 being restored in New Zealand for an American collector.
N.