When Hercule Poirot (Peter Ustinov) examines the hotel register for signatures of previous guests, he discovers the names of several international celebrities during the 1930s, including Cole Porter, Ivor Novello, Maurice Chevalier, Fred Astaire, Adele Astaire, Charlie Chaplin, and possibly Marlene Dietrich (an entry listing a home address is listed as Berlin, although the signature is illegible aside from the capital M and D). The register is likely a private joke by the filmmakers since it appears on-screen for only a brief second or two.
Despite being cheaper, less starry and less ambitious than its two predecessors Murder on the Orient Express (1974) and Death on the Nile (1978), both big hits - this movie was a huge money-loser and put an end to the Agatha Christie franchise of producers John Brabourne and Richard Goodwin.
Guy Hamilton: (At around three minutes) The pedestrian passing the offices of the insurance company.