David Niven was a fan of chess. Peter and June play chess while they await Dr Reeves. Then Conductor 71 "borrows" a chess book Peter has accidentally knocked off the table, Alekhine's "My Best Games of Chess". After the trial is won, Conductor 71 throws the book from the stairway; June finds it in his jacket pocket "to serve the 'was it a hallucination or did it really happen?' motif of the film", according to Mig Greengard. He also noted, "Lots of chess in movies past and present, but I can't recall another prominent appearance of a real chess book".