Full Salvador Dalí-designed dream sequence in Spellbound (1945, dir. Alfred Hitchcock)

"Traditionally, up to that time, dream sequences in film were all swirling smoke, slightly out of focus with all the figures walking through the mist, made by dry ice with smoke pumped across the top. It was convention. I decided to do these hallucinatory dreams in this style, which was just the opposite of the swirling misty dreams. I could have chosen [Italian surrealist] de Chirico, Max Ernst - there are many who follow that pattern, but none as imaginative as Dalí."

-Alfred Hitchcock