Greg Morris and Peter Lupus were the only original cast members to remain on the show throughout the entire run, although Lupus was replaced by Sam Elliott for approximately half of the episodes in season five.
When selecting agents from the I.M.F. folder, the pictures of the agents selected for the mission were almost always in color. Rejected agents' pictures were in black-and-white.
When Greg Morris was invited to the premiere of "Mission: Impossible (1996)", he was so upset by the plot, he walked out. Peter Graves was also upset that Jim Phelps was portrayed as a double-agent.
For several years, the series' first season was not shown in syndication, due to the fact that many people had grown so accustomed to Jim Phelps (Peter Graves) being the leader of the team that many viewers were shocked when they saw the first season reruns with Dan Briggs (Steven Hill) as the leader of the I.M.F.
Cancelled in 1973, it was the last survivor of the 1960s spy series craze that had produced shows like "The Man from U.N.C.L.E. (1964)," "Secret Agent (1964)," "Get Smart (1965)," "The Wild Wild West (1965)," et cetera.