In the opening scene the current date on the chalkboard shows 6/12/1983 but the movie is supposedly 1986
At about 56:51 of the film, after Minnesota gets confronted by the rightful owners of the skateboard he's riding and Pots and Pans start shooting bb's, there is a Tommy Lasorda gnome bobblehead in the hideout. This was an LA Dodgers promo giveaway from 2015.
Towards the end of the movie, there is a newspaper with the date July 8, 1983; although the movie is supposed to be set in 1986.