I recently bought a Minolta film camera and it had some film with it. The film is dated 1991 - 1994. Can I use the film?
Can you use it? Of course... no one would stop you, but if you mean what results you'd get, odds are the film will be darkened along its edges by light leakage, and there may have been some chemical reaction with the air. If it is monochrome film, though, and the camera was not subjected to high temperatures (over 25 C) or high humidity, the film may work fairly well. In that case, I'd use the roll and develop it as an experiment, if nothing else.
Color film, though, is more subject to deterioration and you may find processing difficult. Kodachrome II, for example, used a process with chemicals that pose disposal issues. You might be able to process it as monochrome though.
BTW, undeveloped photos of an Antarctic expedition survived ~100 years, and look surprisingly good with modern processing! So 20 years is not so much...