What was the first film to have an extra scene after the credits?

The earliest film with an extra scene is not recorded. But way before Ferris Beuller's Day Off, several of the Pink Panther films and the Burt Reynolds pictures had out-takes and bloopers from the filming after the credits.

Burt Reynolds' website says this:

"His film The Cannonball Run (1981) was one of the first to include outtakes in the credits, beginning a trend that continues to this very day. "

Hal Ashby's classic film, Being There, (1979), featured outtakes with the credits of Peter Sellers breaking up several times.

In the films, Airplane, and Airplane 2, there was a brief scene after the credits.

Here is a website that I found, "Crazy Credits', that lists dozens of films with humorous credits, or films with additional scenes after the credits, or bloopers with or after the credits.

http://lavender.fortunecity.com/willis/445/cc.html