His acting career began in the early 1980s, landing guest roles on mainstay sitcoms The Golden Girls and Night Court, and appearances in Who's Harry Crumb? and My Stepmother Is An Alien. His distinctive face and demeanor were featured prominently in 1989's Back to the Future Part II, as the high school student who thinks that Marty has just robbed Biff of his wallet. As Biff regains consciousness after having been knocked out by George, Mann (credited as "CPR Kid," but later labeled by fans as the Wallet Guy) shouts "I think he took your wallet!" after Biff, then turns back to the other onlookers and repeats "I think he took his wallet."

Mann also starred in one of the popular Fairfield Inn by Marriott television commercials in the mid-1990s. He portrayed a traveler desperate for a restroom who finds one at a desert gas station, only to be locked out by a child who only uses it as a playhouse. Mann's character portrays comedic "desperate" antics while waiting, but the child never comes out. The tagline for the commercials were, "Traveling's an adventure, where you stay shouldn't be."

Since then, he has appeared mainly on television (including an appearance as Murphy Brown's sixty-ninth secretary), mostly via guest appearances on sitcoms, with movie roles coming only occasionally now. He has appeared in the following films, as of 27 April 2006: