Near the end of "The Pied Piper Power Play" when Nimnul's lair was about to explode and Dale, Monty and Gadget, along with alot of other mice, were locked in cages. Even though Chip and Zipper could save themselves, they chose not to and decided to go down with the others. Fortunately, Monty's lucky toothpick helped pick the lock of the chains holding the captives, but still, Chip and Zipper choosing to die along with their friends was really noble.
Gadget cheering Tammy up and rescuing her from Fat Cat's headquarters in "Adventures In Squirrelsitting".
From "Seer No Evil": Zipper hugging Chip after he chooses to risk his life and defy Cassandra's prophecy to save his friends when he runs under the elephant he thinks is going to crush him.
Dale's absolutely adorable reaction to finding out that Chip is still alive in the same episode. He basically pounces on Chip and hugs him with his little tail wagging like crazy.
Spunky, the courteous and affectionate kitten in "Catteries not Included" who eventually wins Monty's grudging approval.
The fact that in "To the Rescue Part 3", we learn that Geegaw wanted Monty have the Screaming Eagle plane. Whatever happened in Zanzibar, clearly Geegaw didn't hold a grudge against Monty.
In "To the Rescue Part 4", Chip and Dale tell Gadget to take them back home. Monty sadly replies: "At least someone has a home to go back to." and then Gadget gently pats his paw.