In many ancient cultures, notably Greek, people with red hair were believed to become vampires upon death. It is quite fitting therefore, that Johnny and Dennis have red hair. It is unknown, however, if this is an intentional reference.
As of now, this is the most successful movie of Adam Sandler's career, taking in over one hundred sixty-nine million dollars domestically. Previously, his biggest hit was Big Daddy (1999), making one hundred sixty-three million dollars. That film, however, is still his biggest live-action movie.
Although the Villainous Chef of the Hotel Quasimodo and his Rat Esmeralda do not return in this movie, they do appear in the film's video game adaption, where they've been shown to have reformed since the events of the first film.
At the beginning of the movie, during the Columbia Pictures logo, the Torch Lady turns into Mavis as a bat, who then turns the page to the first scene. You can tell it is Mavis and not Dracula because Mavis has blue eyes as a bat while Dracula has red eyes. This sequence also happens at the beginning of Hotel Transylvania (2012).
Jonathan and his family's last name Loughran is a reference to actor Jonathan Loughran, who frequently appears in most of Adam Sandler's films as the frequently seen blonde headed guy who is cross-eyed, most notably in Grown Ups (2010).
This is also the third time Rob Riggle had been in a sequel, but his first animated sequel. He was in Dumb and Dumber To (2014) and returned with his role as Mr. Walters in 22 Jump Street (2014). He was also the skeleton husband in Hotel Transylvania (2012). Coincidentally, he played a villain in all three of these films.
The wooden mask seen on the wall of the castle on several scenes could be a reference to a similar mask given to Nick Offerman's Ron Swanson in Parks and Recreation (2009). Leslie Knope and Ben Wyatt gifted the mask to Swanson when they returned from their Hawaiian honeymoon.
As Dracula (Adam Sandler) was talking to Dennis (Asher Blinkoff) in the car before Frankenstein (Kevin James) turns up the volume on the radio, you can faintly hear the song "Worth It" playing in the background.
Only film in the Hotel Transylvania franchise to not release the same year as a film in Disney's Wreck-it Ralph franchise. Hotel Transylvania (2012) released the same year as Wreck-It Ralph (2012), while Hotel Transylvania 3: Summer Vacation (2018) released the same year as its sequel Ralph Breaks the Internet (2018). Though this movie did release the same year as another video game themed movie, Pixels (2015), which was also distributed by Columbia (the distributors of films by Sony Animation).
Recurring Theme: Disguising humans/judgment of humans. In the first movie, Johnny is disguised from the rest of the hotel and Mavis. In this movie, Johnny is disguised again, as well as his side of the family, when Vlad comes to the birthday party.
Recurring Theme: Acceptance of humans. In Hotel Transylvania (2012), Dracula finally accepts Johnny and his kind. In this movie, Vlad, Dracula's father must do the same with Dennis and his human background.