The Glomp: Hiccup does this when he reunites with Mirabel...then panics when he realizes what he just did and starts apologizing.
Heroic RRoD: Hiccup looks so hard for a missing Mirabel that he passes out from exhaustion.
Instantly Proven Wrong: When Bruno meets Toothless, he asks about his name, as the dragon definitely has teeth...cue Toothless retracting his teeth, scaring Bruno and all of his rats.
Karmic Jackpot: Like in canon, the townsfolk all pitch in to help rebuild the Madrigal's home.
Moving the Goalposts: It's acknowledged in the text that Hiccup assisting in rebuilding Casita gives him an excuse to hold-off repairing Toothless's prosthetic so that he doesn't have to leave so soon (as per his agreement with Alma).
