Because Bobby Moynihan couldn't shave off the beard he grew for Me, Myself and I (2017), they simply applied white make-up over it.
One of "Raincoat Man's" first victims announces that he got a package of "tropical Skiffles" while trick-or-treating. In the Saturday Night Live (1975) sketch "Rap Song," about a rap song with too many featured artists (from the episode Dwayne Johnson/Katy Perry (2017)), one of the rappers is named Skiffle. That same sketch features a cameo from Tom Hanks as "David S. Pimpkins," a gangsta rapper alter ego of David S. Pumpkins.
During the rally, we can see a little kid disguised as Kevin Roberts, a character that appeared in Larry David/The 1975 (2016).