Craig is driving the street in a red 1965 Plymouth Fury convertible (note vertical headlights.) He then spots Diane walking down the sidewalk. When he hurriedly pulls over to the curb the car changes to a red 1965 Dodge Coronet convertible (horizontal headlights.) Dr. G comes to Diane's rescue, and when his limo pulls away we see the Fury convertible parked at the curb.
When Craig and Todd are driving the black 1955 Cadillac Fleetwood 75 limousine to get away, the scene changes to showing them through the drivers' door window but the door vent glass is not of a 1955 Cadillac but from a 1957 or 1958 model. The next interior shot shows the same 1957 or 58 model with a customized dashboard. When showing the drivers driving the 1955 through the windshield, a solid black steering wheel is shown that a Cadillac of these vintages never had. When the 1955 Limo is "blown up" by Dr. Goldfoot, the pieces remaining of the Cadillac are showing a "correct" gray and dark gray steering wheel which is correct for a 1954 or 1955 Cadillac so the Limo was not harmed in making this movie.
During the chase scene, Dr. Goldfoot and Igor on the motorcycle are less than a block behind Craig and Todd in a red convertible. One reverse shot at the top of the hill shows the motorcycle and sidecar from behind, with no other cars on the street all the way to the bottom of the hill, several blocks away.
One gag scene has Uncle Donald repeatedly banging his head on a low-hanging metal lampshade suspended directly over his desk. But at the end of that scene in a longer shot, the lampshade has suddenly disappeared, nor is it seen later, in a subsequent scene that takes place in his office.
During the chase, when Craig and Todd are on a motorcycle, the footage projected behind them is off scale. The cars they pass by were shot at too close a range, and appear far too large compared with the actors.
During the chase scene at the end, the "cable car" with Dr. Goldfoot and Igor goes off the tracks to continue chasing Craig and Todd over streets and over the Golden Gate Bridge, which have no tracks. San Francisco cable cars run by grabbing a moving cable beneath the street, controlled by the lever you see the drivers of the cars handling. The red "cable car" is obviously a motorized trolley car.