The dog is behind it all
Edit: So I was drunk when I wrote this cuz I just saw the movie last night and drank the whole time. I thought that the dog being wet was a weird thing and thought it would come back to something but it never did. I tried searching to see if anyone else wondered why the dog was wet but didn't find anything. I'm glad to see people enjoyed the post and that we all agree the dog is the mastermind of everything! ❤️
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When the lights first happen, the bow and arrow boy goes outside to look at the dog and he says the dog is soaking wet.
That's because the dog has already teleported and landed in the pool. That dog is a different dog.
That's why when they jump through the time travel ball the dog just knows what to do because he's done it before.
The dog was gone most of the movie setting everything up. Just like Jigsaw or Kevin from Home Alone. He had to make sure everything was how it should be.
You're welcome.