I know I talked about time travel yesterday, but let me talk about it some more! There was some neat time travel in Harry Potter and the Cursed Child. I'll try not to spoil the story.
Part 1 has a Time Turner, which lets you travel to any point in time within the past 50 years or so. The play isn't specific about how far back it can take you. But the play is specific about the five minute time limit. You can spent 5 minutes in the past, at maximum, before getting sent back to the time you left from.
That's a really neat idea! You can only visit the past for a brief period of time. So if you're trying to do something specific, you have to move quickly! I don't think I've seen that before. Sure, Back to the Future has something similar, where Marty has to do something before he disappears, but that's more of a general time limit, not a specific five minute limit. I could imagine someone building a good story around this.
Sadly, the play doesn't have much use for the five minute time limit. Both times our heroes time travel, their mission is very specific: cast one or two spells, without being seen. So really, they're in and out of time in under a half-minute anyway. They never even come close to reaching the five minute danger zone.
Of course, both times they time travel, they end up making a big mistake that drastically changes the future and sends them into bad, alternate timelines, like Back to the Future Part 2. In the first bad timeline, Harry and his friends all kinda hate each other. In the second bad timeline, Harry failed, and Voldemort conquered the world.
There is a final time travel episode, one where Harry and friends get in on the time travel fun, but I'm not sure how to describe it without spoiling things.