The closing credits bill the cast by referencing the whodunit plot and playing on the words of the theatrical convention of "in order of appearance" by billing the cast "in order of their disappearance".
The end credits list the cast in order of their "disappearance". However, they are out of order. Stephane Audran is listed before Alberto de Mendoza, even though his character died before hers. And Elke Sommer is billed before Oliver Reed, yet he is supposedly killed before her.
Although it is supposed to be night when the second victim is killed (darkness can be seen through the windows), it is clearly broad daylight during the exterior search scenes.