The jacket that Robert Redford wears for most of the film is the exact same jacket he wears in "The Natural" - he got to keep it after filming had finished, and wore it for this film as well.
When they are going through the computer guy's trash, Mother (Dan Akroyd) is wearing an "Aleka's Attic" t-shirt which was River Phoenix's (Carl's) band.
Dan Aykroyd's character mentions in the movie that he feels the NASA moon landings were all hoaxed. Years later he appeared in a UFO documentary that also discussed this same theory.
Mother is also seen wearing a T-Shirt with the band "The Tragically Hip" on it. This is Dan Aykroyd's favorite band, and also the band he chose to play on the 1975 SNL show that he hosted.