The producer, Jennings Lang, offered a cameo role to his friend Walter Matthau. Matthau accepted, without compensation, on the condition that he be billed under the name "Walter Matuschanskayasky," the last name being a long-standing "inside joke" that he had used for decades. The role was originally scripted as "a drunk sits at the end of the bar", which was expanded by writer George Fox, giving the character lines of dialogue (involving toasts to celebrities). When the film was completed - as agreed to by Lang and Matthau - "The Drunk" was credited as "Walter Matuschanskayasky." This led to a long-standing (and false) rumor that "Matuschanskayasky" was Matthau's real last name.
In a bizarre coincidence, the location on the first day of shooting was rocked by an earthquake. In an even more bizarre coincidence, an earthquake also struck the location where the last day of shooting occurred.
Before stereo television sound was commonplace, NBC aired the movie with the soundtrack simulcast on local FM radio stations, so that viewers could re-create "Sensurround" at home.
In the scene where Stewart Graff (Charlton Heston) is running lines with Denise (Geneviève Bujold), the script he is holding is actually for this movie and is on the page for the scene being shown.
John Williams composed the score to this and The Towering Inferno (1974) concurrently. Having previously scored The Poseidon Adventure (1972), he briefly earned the nickname "King of the Disaster Scores".