When George and Jerry are in the back of the police car, George makes a crack about the window and tries to get Jerry to roll it down, tricking him because there are no locks or window handles in police cars, as Jerry finds out when he can't roll down the window. However, when the police go to arrest Kramer, they go into the building and Jerry reaches out the open window to open the door (which also clearly has a lock). And of course, the criminal the cops picked up earlier escapes and is later revealed to be a serial killer as well.
When Jerry, George and Kramer are talking on the bench, George lifts up his sandwich to take a bite. In the next shot, the hand with the sandwich is back down by his lap.
When the cop car gets the notification to help apprehend the smog strangler, they show a scene where the cop car makes a left turn. After completing the turn, the back seat is clearly visible and it is empty.
When George and Jerry are in the back of the police car, the two cops spot someone breaking into a car and call it in as a "519". In Los Angeles, the dispatch code for auto theft is 503.
Jerry is talking about the 12-gauge shotgun in the police car. George remarks that the 12-gauge "makes the 11-gauge look like a cap pistol." However, when referring to shotgun gauges, an 11-gauge is actually larger than a 12 gauge.
After the police arrest Tobias in front of the Bicycle Shack, they drive away to the station, but when they receive a radio call the car is seen passing by the Bicycle Shack again, a place they should not be near.