Plot hole: The film takes place around 1980, i.e. when it was filmed. But Steve Railsback appears too young for the Vietnam veteran he is playing, and in any case he has meant to have come back from the war, immediately committed a crime, and been on the run since. This would only be possible if he had been on the run for a decade, with the police in hot pursuit for all this time: that is extremely unlikely. These inconsistencies are actually a reflection of the fact that the film was scripted a decade before it was shot.
Suggested correction: Cameron is not too young for the timeline of the film. Steve Railsbeck was born in 1945. The first US troops arrived in Vietnam in 1965. If Cameron did a one year tour of duty between 1965 when he was 20 and 1969 when he was 24, that gives him a year to be discharged, return to the USA, commit a crime, and be on the run for ten years or more by 1980. Wikipedia lists 120 criminals who have been on the run since 1970 - and that's just the famous ones.