Angela Lansbury had appeared in Death on the Nile (1978). The title is a take off of that Agatha Christie work. Lansbury's character in that film was Salome Otterbourne, a name close to Sally Otterburn. Like Jessica Fletcher, Salome Otterbourne was an author.
At one point, Jessica Fletcher (an American) is told to return the Rosetta Stone to Egypt. She replies "For that, you'd need to speak to the English." Angela Lansbury who plays Jessica Fletcher, is, in fact, English (born in London).
Many of the Egyptian characters speak with a French accent and/or pronounce some French words---such as crème de la crème---flawlessly.
Turhan Bey was not Egyptian. However he stared in one of the original Universal Mummy movies: The Mummy's Tomb in 1942.
Although set in Cairo, Egypt, no scenes were filmed there.