In Chapter 16 of
Witch Watch, the character Nico Wakatsuki yells out "MURI MURI MURI MURI MURI!" and Kanshi Kazamatsuri asks if she's trying to be
DIO, referencing his "MUDA MUDA MUDA MUDA!".
In the author's note of Volume 3, Kenta Shinohara says that he and his assistants like having background noise on while working so that it isn't too quiet in the workplace. They try to put on things they all saw already or stuff they can follow just from the dialogue so they don't get distracted. After trying out a few, the winners were JoJo's Bizarre Adventure, Oishinbo, How Do You Like Wednesday?, and other similar series.
In Chapter 35, a character named Jun Horai says that he likes Giorno Giovanna and Josuke Higashikata from JoJo's Bizarre Adventure in response to being asked whether there's a girl he likes.
At the end of Volume 4 on the Special Thanks page, Jun Horai does the pose of Jonathan Joestar from Volume 4.
In Chapter 38, a character named Tenryu Kiyomiya has his hand stuck to his hat at all times. It's stated that this is a phenomenon similar to how Jotaro's hat and hair became one object.
In Chapter 82, a character complains about a Nile Tsetse fly being in his ramen and asks if he's in Egypt, referencing the fly that appeared in Hermit Purple's photo of DIO in Chapter 121.
In Chapter 90, Nico Wakatsuki mentions that it's a natural law that people with similar vibes tend to attract. Another character tells her not to describe it like she's a Stand user and that the law doesn't exist. This is a reference to Toshikazu Hazamada telling Josuke and Jotaro that Stand users attract other Stand users in Chapter 294.
In Chapter 103, a character named Rui Fujiki starts acting like Purple Haze after consuming an experimental energy drink. He also screams "BASSHAAAA" like Purple Haze afterward.
In Chapter 169, a genie character named Slump is compared to being a Stand like Star Platinum.
Volume 4's Special Thanks