Filming was very difficult for the 71-year-old Burt Lancaster, as he had undergone a quadruple heart bypass operation two years earlier. There was some question as to whether he would even get insurance for this film.
Huge cards were necessary on the set to help Burt Lancaster's fading memory, and he also had problems to read those cards.
Some crew members said that Burt Lancaster and Kirk Douglas did not talk to each other off the set.
After the police fire at the train, Sgt. Deke Yablonski (Charles Durning) says, "What is this, Gunfight at the O.K. Corral?". Burt Lancaster and Kirk Douglas both starred in Gunfight at the O.K. Corral (1957); Lancaster played Wyatt Earp, and Douglas played Doc Holliday in the classic western.
Red Hot Chili Peppers played themselves in the movie. They were big on the local scene but wouldn't crack the big time until the album "Blood Sugar Sex Magik" in 1991.
Last of the seven films that Kirk Douglas and Burt Lancaster made together starting with I Walk Alone (1947)).
Doyle L. McCormack, who played the train engineer, is the real-life engineer and chief mechanical officer of the SP #4449.
Adolph Caesar was signed on to play Leon Little. However, in the weeks of filming, Caesar died of a heart attack and Eli Wallach took over his role.
Fran Drescher and Jennifer Tilly both auditioned for the role of Skye. Moreover, Darlanne Fluegel fired her agent because he was against her playing Skye.
During the shootout on the train the Eli Wallach character says "top of the world ma". This is a reference to the famous James Cagney movie, White Heat (1949), released in 1949, and regarded as one of the great classic gangster movies.
The locomotive used was the real Southern Pacific Daylight 4449. During the crash scene, they used a life-size model of the SP 4449 to simulate the crash.
In the closing credits, there is a credited production consultant named Issur Danielovitch. This is Kirk Douglas ' birth name.
The last shots of the train used a full-scale wood and fiberglass mock-up of Engine No. 4449 and its tender (only built above the wheels, and only the right side finished); it wound up stored inside a service station in Desert Center, CA, and was sold at auction November 2, 2019 for $130.00 - it was in rough condition by then, but the cab door that Burt Lancaster and Kirk Douglas step out of was intact.
The engineer driving the SP 4449 is the actual engineer and mechanic of it: Kirk Douglas.
At one point Tony Curtis was being considered for a role, possibly the Eli Wallach part originally intended for Adolph Caesar. Curtis had worked with Lancaster on Trapeze (1956) and Sweet Smell of Success (1957) while he had appeared with Kirk in The Vikings (1958) and Spartacus (1960). All three had appeared together in John Huston's underappreciated romp The List of Adrian Messenger (1963).