Actually Pretty Funny: Downplayed. Camilo shapeshifts into a very short version of Stoick, calling himself "Stoick the Emotionally-Unstable". Gobber finds it funny, but doesn't admit so out loud.
Contrived Coincidence: The Cove where Hiccup tamed Toothless was also the place Stoick proposed to Valka.
Dramatic Irony: Hiccup assumes Stoick attacked Mariposa out of a general blood-lust and hatred of dragons, unaware that it's more personal than that.
Major Injury Underreaction: Hiccup managed to block a blow from Stoick's axe using his arm, too pissed at him to really pay it any mind.
Mythology Gag: The flashback to Stoick meeting and proposing to Valka is very similar to Alma revealing Pedro's fate in Encanto.
Not Quite the Right Thing: Here we find out that Stoick's parenting was based on incomplete information, culminating in Parental Neglect born from over-rationalization. The reason why he forbade Hiccup from training in early adolescence was out of the belief that he could seriously hurt himself due to a lack of coordination, causing him to be alienated from kids his own age. This caused Hiccup to try and learn and handle weapons all on his own, which Stoick misinterpreted as his son lacking an attention span, making him take an apprenticeship with Gobber so that someone would keep an eye on him ("basically a babysitting job, disguised as a mentorship"). Since Stoick forbad him from being involved with responsibilities kids his age attended, the rest of the village began to resent him for "cowering" in the forge. When the other kids start bullying Hiccup, Stoick did nothing about it under the assumption that it was just "roughhousing" to toughen him up.
What started as a promise, to protect his fragile son... Turned into years of neglect, in a failed attempt to strengthen him. To break him down into what he thought he needed to be, instead of nurturing who he was. The boy wasn’t completely innocent in all this. Those faulty inventions did cause a lot of damage. A bit of his reputation was earned. But he was only so insistent on making them, because he was desperate to prove to his father that he was worth something. When the man had viewed him as useless. Something to be changed into something else. Into something more valuable.
