At the beginning of the movie, F-4 Phantom fighters are seen with AA designation on their tails. AA aircraft were assigned to the USS Forrestal. Future Senator/Presidential candidate John McCain who spent several years at the Hanoi Hilton after being shot down while flying from the USS Oriskany, also flew previously from the Forrestal. He narrowly escaped death during the tragic Forrestal fire in 1967.
The Time magazine cover that was supposed to be Col. Cathcart was an actual cover. It depicted LTC Robinson Risner who was shot down on 16 September 1965. At the time he was the commander of the 67th TFS.
The plane at the end of the film was a C-141 stretch: an extended C-141 aircraft. They did not start extending the C-141 airframe until well after the Vietnam conflict ended.
When Williamson is talking to Ashby through the transom in the cell, he asks him to explain about Rod Steiger helping Omar Sharif. Ashby replies with a comment about Julie Christie. They are discussing the actors and plot of the movie "Doctor Zhivago."