Maxwell's screen debut was in the 1974 film Young Frankenstein, where he played one of the title character's medical students. Most of his roles have been in bit parts or as guest appearances on television series.
In 1997, he published a cookbook, Secrets of the M*A*S*H Mess: The Lost Recipes of Private Igor.
Maxwell is a regular participant on the alt.tv.mash newsgroup where, along with series writer Larry Gelbart (up until Gelbart's death in 2009), answers fan questions about the behind-the-scenes workings of M*A*S*H.
Maxwell (according to journalist Peter Palmiere) has been working on a video documentary about female judges and referees in the sport of boxing.