Subliminal Messages - Narrative and Homage

As in an earlier post i mentioned the scene in Sin City of Kevin on the porch was paying homage to the original comics, this can be regarded as subliminal messaging.  This is one of the areas i'm interested in as it directly links to an original narrative that causes an emotional response even if previously known or in this case one that i hadn't until after i checked it out.

Having recently watched the final episode in this series of Doctor Who - The Wedding of River Song i can see now the whole of Doctor Who has been paying homage and also using subliminal messaging to propel the stories and the whole series.  Like a detective show, the clues are actually in the visuals.  whether it's part of the set, the audio (the cloister bell especially) or characters, they are all interwoven and gradually become clear at the very end or when you look back.  The "question" that has been unanswered during this story and was supposedly taboo has been there right from the start in 1963 right under our noses "Doctor who?" this not only pays homage but also opens up to another series of stories, such as finding the answer or actually understanding the question (as in Hitchhikers Guide to the Galaxy)
guardian.co.uk-doctor-who-wedding-of-river-song

subliminal messages can also be see in links to spin offs such as The Sarah Jane Adventures and Torchwood