Richard Attenborough was a late replacement for James Mason. Attenborough only took the role to get funding for Gandhi (1982) which would take another seven years before it went before the cameras.
Despite a few small changes made to fit the different cast, the dialogue for this movie is almost word for word identical to the 1965 version.
The Abbasi Hotel (formerly known as the Shah Abbas Hotel) is a hotel located in Isfahan, Iran. The hotel is in the center of an Iranian city, so the external shots were shot elsewhere. Also filmed in Spain.
The name of the screenwriter, Peter Welbeck, was a pseudonym for Producer Harry Alan Towers. This was the second adaptation of Dame Agatha Christie's "Ten Little Indians" that Towers had worked on under this alias, having previously co-written Ten Little Indians (1965).