In "Lost and Found in Translation" the Dino Thunder Rangers sit down to watch a dubbed episode from their Japanese counterpart Abaranger and admit at the end that it's a really good show. It's one of the very few times Power Rangers has recognized its Japanese origins in-show and it's used to basically shake hands with the Japanese team.
Trent and Anton's parental relationship. Their relationship may be strained most of the season, because of Mesogog, but thanks to the Rangers and some Character Development, they have some Aww, Look! They Really Do Love Each Other moments. The fact that Trent has already been referring to Anton Mercer as "Dad" since Mercer's first appearance is proof of this.
Tommy's encounters with all his past Ranger forms in ("Fighting Spirit"), that and CMOA.
In "Bully for Ethan," while looking through items in the lab, Tommy comes across a group photo of the original MMPR team.
Cassidy, the Intrepid Reporter she is, managed to get (with Devin) footage of the Rangers morphing. This is the tape that could make her career... And she hands it off to the Rangers with a smile, choosing to protect her friends over stepping on them.
The Cassidy/Ethan fling - they seem like polar opposites, but when they're paired up by a dating site, they actually try it out, rather than simply ignore the results. It doesn't stick, but it's nice to see that they were willing to try. Even better is that when Kira finds out Ethan has been talking to Cassidy, his first response is to ask Kira to give Cassidy a chance at being friends.