Was Wagner's Prélude from the opera used?
The Liebestod was incorporated in Luis Buñuel and Salvador Dalí's Surrealist film Un Chien Andalou.
In Alfred Hitchcock's 1930 film, "Murder!", Herbert Marshall, Sir John, is shaving himself while BBC radio is playing Wagner's Prélude from Tristan und Isolde. But not the liebestod motif is on the soundtrack.