I'm usually oblivious when it comes to subtle changes when it comes to evolving OP/ED animations, but the last ten seconds of the Oregairu Zoku OP keeps changing in ways that even I've started noticing differences.

In episode 5, the camera has zoomed out enough that we can see the benches behind Yukino and Yui.

Episodes 3 and 4

Episode 5

The room changes by the episode.

Episode 3

Episode 4

Episode 5

The cups at the end haven't changed yet, but the table itself has.

Episode 3 and 4 (red line added for comparison)

Episode 5 (red line added for comparison)

Speaking of cups (and the tea set), they've become a bit of a running gag much like how the number of stickers on the classroom plate keeps changing. On occasion, the camera will focus on the cup representing the person talking i.e. Hachiman in episode 1 and Saki in episode 5 (not pictured below).

Episode 1

Episode 3

Episode 4

Episode 5