Just to give some extra context to the fight scene at the end: In-game Ekko’s signature ability is to rewind time a few seconds, I believe both Ekko swinging the clock (and constant ticking noise in the BGM), as well as the whole playing out the action scene with them as kids and then rewinding to play it again real time, is a nod to his character. I guess he deserved some addional attention after being left with no screentime for so many episodes.
Generally I think the creators did an amazing job with making some of these creative references while keeping the characters and storytelling at the forefront. And I totally agree, this fight scene was probably what left the biggest impression on me overall in the entire series, it is really well done.