(at around 21 mins) When Jay and Silent Bob are first driving in the car with Merkin, they pass by the same large multi-level building twice. It is seen outside the driver's side window and is obviously a rear projection plate.
(at around 59 mins) The camera is reflected in the window as Milly gets out of the van to admire the Hollywood sign.
(at around 24 mins) There are palm trees visible outside of the Mooby's that is supposedly located in Chicago.