What was the hardest thing for you to understand on your first watch of tenet?

I see so many comments and posts of people not understanding, needing multiple watches, or even getting more confused after multiple watches.

I watched the film on my phone starting at midnight in bed… intending to save half for the next day, but ended up hooked and watching it all.

But I genuinely think I understood almost everything. I thought they explained everything in the film, enough for the film to work.

I came away thinking a lot about how the bullet holes appear in walls for forward perspective people, in a room that they later have an inverted person pull the bullet out of. Even asked that on Reddit, only to realise from comments that they explain that in the film too, with the “pissing in the wind” metaphor.

Obviously I couldn’t explain the intricacies of Sator and TP interrogation in both directions, and there are interpretable things like how many things Neil actually did, but all of the plot points, all of the fighting, the turnstiles, the temporal pincers, the algorithm, the general inverted object interactions, I feel all of that was explained and presented in a manor that was fully understandable. (Not trying to be all like “look at me I’m so smart”, I genuinely am just curious to hear other opinions and takes)

So, interested to hear which pieces did you guys specifically need a bit of discussion or extra thought on to fully grok?