These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Harsher in Hindsight: Pronyma abandoning the child she cared for in the woods turns out to be this when it turns out that it's Kiku.
Heartwarming In Hindsight: Byakuya's kiss with Raine in Unreal Society becomes this much later on when he decides to marry her.
Near the end of Return of the Samurai Sheena says to Ichigo that Mizuho is moving again, but she won't say where. It turns out to be Karakura Town.
Hilarious in Hindsight: The snippet in chapter 11 of Unreal Society about camping outside becomes incredibly funny after this gem from the English Dub in the Turn Back the Pendulum arc
Mashiro: I'm not really a tent person
Kensei: Sorry, we're all out of five-star hotels.
Uryu saying he's the student council president in chapter 38 of Unreal Society. At the time of writing Bleach's Time Skip had yet to occur.
Ho Yay: Ichigo and Lloyd, Byakuya and Kratos, Regal and Chad, and Ichigo and Emil, just to name a few sets.
Les Yay: Rukia and Colette, Pronyma and Orihime, but there are plenty of other sets.
Narm: After the incident with Aizen regarding the Derris Emblem you kind of expect the illusions that affect the other soul reapers.
Rukia begging the wild rabbit she has to live. There's no buildup to the sentence at all you almost expect Ichigo to make a comment about how it's Just A Flesh Wound.
Unexpected Character: Shunsui joining the party rather early in Unreal Society and staying with them throughout the entire journey is this to some considering how little interaction he has with Ichigo and is not one of his regular companions.