... his own motorcycle stunts in The Great Escape, with the possible exception of the fall, for insurance reasons. I'd have to look that one up.
He was also one of the first, if not the first, TV actors* to make the transition to movies. For reasons that defy comprehension, Hollywood didn't want to let TV actors make it to the silver screen.

* He played Josh Randall in Wanted: Dead or Alive, with his sawed off lever action Winchester, which was chambered for 30-40 Krag, I think, rather than the standard 30-30. Back then, a Winchester was often chambered for the same round as the Single-Action Army Colt revolver, so one didn't have to carry two different bandoliers of bullets.

by requesting a "modified Steve McQueen."

Which inspired my mother to start asking the lady at the beauty parlor for a "modified Vanna White."

We made our own fun.