Reincorporation is an important part storytelling. In fact you can't tell a story without bringing things back from earlier. If you don't bring any information back or continue any things that are set up, you aren't telling a story but simply saying a bunch of random stuff. It's also an important part of comedy. Catchphrases and running jokes are clear comedic examples of reincorporation.
Reincorporation, if you're not familiar with the term and not worked it out from the beginning, is reusing something you set up earlier in a scene or story or show. In James Bond movies, James is given some innocuous looking gadgets by Q whilst Bond goofs off to distract you from how important these objects are. They are in fact magical weapons in terms of mythical hero's journey. Later on these objects are reincorporated at a key moment to save our hero.
Reincorporation being important in storytelling has two main implications. Firstly that if you establish something, it should used or referred to later on. The Russian author and doctor Anton Chekhov is credited with outlining this by stating that if a gun is set up in act one, it should go off by act three. In writing this means don't set up more than you need. Everything should have a purpose. Even if that purpose is not to be reused, but to be there to illustrate character, the severity of the situation, etc. In improv this means use what you set up.
Creativity in stories, is not, as it first appears, simply about creating new things, but much more about using and reusing the things that are set up.
One thing I've learned performing improv, and had highlighted by doing solo shows, is that there is no such thing as a throwaway line. Everything has meaning. And I don't just mean the lines said by other characters, I also mean your own lines. So many improvisers, even very good ones who listen so well to what others say, don't listen to themselves. They don't see if they said was what they meant to say, or if they said it how they meant to say it. If you meant to say one thing but said something slightly different (as frequently happens on and off stage), what you actually said is what has been put out there and overrides what you meant to say. If you're not aware of that, suddenly you are not on the same page as your fellow performers who were listening to what you said. If you meant to sound angry, but you realise it came out more as confused, then your character is confused. Use it.
Ideally everything set up will be used somehow. You shouldn't be creating new things if old things are lying unused.
The other implication is that towards the end of a story, you should only be using what has been set up previously. You should have all the information you need to finish the story. If Jack pulls a gun in the final scene to save his life that was never referred to before, this is disappointing. Same with any reveal at the end that was not set up before. A good murder mystery should keep you guessing until the end but when the secret is revealed, it should be so satisfying because all the pieces make sense. Mystery endings where important information had been held back from the reader or viewer so that there would have been no way of working it out make you feel cheated. Endings like this care called "Deus ex machine" or "god from the machine" because it was often how the Greeks ended plays, with a god coming down and magically making everything all right rather than having the characters solve it themselves. It nearly always makes for disappointing endings. Especially to a modern audience who are not used to having gods meddle so much in their stories.
With writing, you have the luxury of what I call preincorporation. This is where you can go back and add information at the beginning of the story once you know what you need at the end. So if the only way for Jack to save himself is to have a gun, then go back and set up early on that he keeps a gun in his third drawer down. Bingo! Goes from deus ex machina to deus ex syrtária.
We don't have this luxury in improv (and don't have to use it in writing). We can be more creative. In improv you need to use what you have set up to help you out. And trust me, something you (or someone) has said or established and can be reused to save you. Remember that chewing gum Jack put in your pocket to keep because Florence had touched it? Yes that.
In fact the skill in movies and books is for the things to be set up and reused just as the audience has forgotten about them being there. It's a subtle balance. The audience must, when reminded, remember what was set up, so it usually has to be more than just something hanging on the wall amongst a whole bunch of things. The audience's attention has to be drawn to it without them being aware of it. If you go in too strong, the audience will realise it's being set up and the pay off won't work. Too subtle and most people won't remember where the thing came from and again will seem like a deus in the machina. A very good way of doing it is to draw our attention to it, but make us think it's served its purpose. Such as the gum in the pocket which was set up to illustrate Jack's obsession with Florence but which finds a new use as the magical weapon that saves him from his nemesis.
In improv, you rarely have the luxury of knowing what objects you will use later. And being subtle about them but remembering them is close to impossible. Ideally you will use all of the objects and ideas you set up. And use them several times. It is way more satisfying to get a lot of use out of a few important objects than hardly any use out of a vast collection of artefacts. As Jack thought popping the gum into his mouth, not only reincorporating it as an object one last time but also using it to illustrate how his journey had cured him of his obsession with Florence.
