In Super (2010), I noticed the weird concept of flashbacks within flashbacks within flashbacks.
Which was the first Hollywood movie with the same concept?
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IMDB flaged also Enter the void (2009) with this technique. Seems that only these movies used this kind of brain teaser. As I found only these titles, i can answer your question saying that Passage to Marseille (1944) was the first movie using this technique. If you are interested you can give a look to the detailed plot here (SPOILER) looking how the flashbacks were actually mixed.