Mitzi's expression and the subsequent hug make it doubly so on the next page.
Yoshi telling Dr. McNinja that he's happy that the doctor is alive. Heck, McNinja saying he's happy that Yoshi's alive counts as well! Considering that these two have had a rocky relationship in the past, only ever working together when Gordito is in trouble, that the both of them are glad to see each other alive and well is definitely a nice touch.
During the montage of various scenes after the humans won the war against the dinosaurs, we finally get to see Gordito and Yoshi reunited. The look on that raptor's face? Yeah, he missed his human.
When Ron, Steven, and the citizens of the Radical Lands arrive in the world, King Radical is just so overjoyed to see them. As terrible as how they arrived is, KR is seeing his friends and people for the first time in possibly years after mulling around in a considerably blander world. Also since the Radical Lands are dying, them appearing means that he's saving lives.
How does Dr. McNinja celebrate defeating King Radical's plan? By calling up a pizza place to get the Friend Brothers back in business as a way to make amends.
The good Doc Mercy Killing his own mentor Ben Franklin, stuck on the Mortal Plane as a headless horseman by finally dealing with his Unfinished Business. Just buying a pizza he promised to take him out to celebrate for.
The last page of "Why a Gorilla?" has two: Dr. McNinja defending Judy against a rude patient and when she thanks him, he responds in sign language.
Dr. McNinja is largely unaffected by the Negazone, an amalgamation of all the worst fears to every intruder trapped within. Unaffected, that is, until Negazone!Gordito shows up and tells the doctor that he is a bad role model.
After some brief resistance and denial, Dr. McNinja finally concedes... by saying he'll have a talk with Gordito when it's over and see what he needs.