Animated World of DC Comics: The Rise & Fall of The Super Friends (1978)

 From Challenge of The Super Friends:

Mr. Mxyzptlk (Frank Welker) decides to torment our heroes by forcing them into a movie of his own making, using 5th dimensional magic. He'd try this again three years later in "Mxyzptlk's Flick", a shorter piece.

Here's "The Rise & Fall of The Super Friends":

A few months after this episode aired, the team met a less threatening, but just as delusional, filmmaker, Frowning Fritz Frazzle, in the Super Friends comic book.

Rating: B.