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Science has largely debunked the effectiveness of subliminal messages (that is, the practice of inserting frames that are too quick for the eye to see into video, in an attempt to shoot them directly into the viewer's subconscious). But that hasn't stopped directors from constantly slipping hidden messages between frames of their films and shows. Nowadays, they absolutely know that you'll spend all day pausing and rewinding to find that stuff.
Or you can let us save you the trouble.