Ashmore appeared in the 1980 hit comedy film Airplane!, Airplane II: The Sequel and films such as Gable and Lombard (1976), Invisible Strangler (1978), Parts: The Clonus Horror (1979), Monster in the Closet (1986) and Extracted (2012). In 1981, he appeared on both Days of Our Lives as a hit man out to kill Julie Williams and General Hospital as Monica Quartermaine's private investigator. He also had a supporting role in the 2012 independent thriller Extracted. He made guest appearances on various television shows including Happy Days, The Bob Newhart Show, Battlestar Galactica, Touched by an Angel, The West Wing and the current version of Hawaii Five-O. In 2010, he had a recurring role in season 4 of The Guild. He voiced Leone "Leo" Galante in the 2010 video game Mafia II, and its sequel Mafia III. He also voiced Austin Buckell in the 2013 video game Dead Space 3.