It's amazing what computers have done for movies and TV. Starships, armies of gladiators, WWII dogfights. Even placing deceased stars in contemporary settings. My favorite was the Ford Mustang commercial featuring Steve McQueen.

I'm wondering if CGI has been used to "shoot around" a modern actor when he or she can't be on the set at the appointed time. ie Shoot his scenes with a stand in and then shoot the missing actor when he finally shows up and insert later.