In the trailer for season 51, Jeff said, "For the first time ever, our entire history — every advantage, every idol, every twist we've ever done, 50 seasons of Survivor — is in play". Here is a curated list of past twists that could come back. If there is ambiguity in the rules of what would resolve for some of these twists, I will provide a more thorough set of rules in the comments. If you believe these twists need further explanation, please tag me in the comments.
On Adding Answers:
I reserve the right to N/A any answer that is not in keeping with the spirit of this market
If an answer is added after that answer has already satisfied the criteria to resolve, that answer will resolve N/A
If there is any ambiguity, I will work with the person who suggested the answer to write a set of rules for the resolution of that answer
Should there be a dispute, the rules provided will control over the answer to the question itself. While, the question is intended to provide an easy way for people to bet on their beliefs, it is not the end all be all, and all traders should look at the rules. Please don't hesitate to ask clarifying questions in the comments. In the unlikely event of significant ambiguity regarding whether the resolution criteria have been met. I reserve the right to resolve a question to a percentage that I deem fair. I will give notice before I do this.
@AaronSimansky contestants are eliminated before the first travel council without being evacuated, ejected, or quitting
@AaronSimansky at least one contestant is offered the opportunity to swap from one tribe to another tribe of their own volition without any negative consequences