Filmed right after_Missing in Action 2: The Beginning (1985)_, this film was supposed to be the sequel. However when the producers realized this film was the better of the two, they simply renamed them and made the other film a prequel to this. This explains why Steve Bing receives a credit for "characters" because he wrote the screenplay for what became the prequel.
Both the North Vietnamese and Vietnam People's Army are seen using the Chinese Type 56 assault rifle - originally produced in the People's Republic of China as a licensed copy of the Soviet AK-47 (when technology transfer between both nations were commonplace) prior to the Sino-Soviet split in 1962.
This was the first film in Chuck Norris' five film contract with Cannon Films which paid him a million dollars per film which was agreed to by Menahem Golan against the wishes of his cousin, Yoram Globus.
After the studio viewed both films, Missing In Action was easily deemed the better of the two films because it was well shot by Director Joe Zito and more action oriented as compared to Lance Hool's Missing In Action The Beginning, which really paled in comparison in terms of overall quality by many in the studio. So they flip flopped the order with the intention of saving/redeeming Hool's film and the strategy proved to be a financial success and the birth of a franchise.