Jonathan states "mon crayon is large" and the French waiter repeats, in English, "my pencil is big." While it is unclear as to whether Jonathan knows proper French, the correct word for "big" is "grand". The French word "large" translates as "broad" in English. The waiter would have said, "my pencil is broad."
In the opening chase sequence, before the credits, the players are seen chasing each other across the campus of UCLA. Several prominent extras playing professors are shown repeatedly walking past them from different directions.
Just before the title of the movie, Jonathan is talking to a girl student holding a can of Diet Pepsi. In-between shots, the can changes position, so the name is still visible, even though she's not doing anything else but holding it.
Near the end of the 4th reel, Jonathan crashes the passenger side of his Mustang into the driver's side of Mr. Bronski's Mercedes sedan. Barely into the the 5th reel, certainly no more than 12 hours later in the screenplay, the undamaged passenger side of Jonathan's car is clearly visible as he pulls into the garage underneath his apartment.
The scenes of "East Berlin" at night are clearly "West Berlin" by the street lighting - "East" Berlin had very distinctive mass produced street lights that are to be found in nearly every town and city of the former East Germany.
When leaving West Berlin with the punks, Jonathan is told that there will be a passport control somewhere on the road to Hamburg. - Actually, there would have been two border controls: first, after crossing the Berlin city borders from West Berlin into DDR, and second, when leaving DDR and entering West German mainland. The second control would have been the more crucial one, as it aimed to prevent illegal emigration of DDR citizens.
When leaving the DDR by foot the border guard asks Jonathon "What was your purpose of visit to East Berlin?" - East Berlin was never referred to as "East" by the DDR as this would lend recognition to the occupying forces of the other side - they would have said just "Berlin" or "Berlin Haupstadt der DDR" (capital of the DDR)- they referred to West Berlin as "Westberlin" or "Berlin (west)"
Registering in the Berlin hotel, Sasha comes first and enters the name Barlickova. The receptionist then asks Jonathan, sneering, "Mr ... Barlickova?" Czech surnames for females always end with 'ova', whereas males don't; if the couple shared a surname, Jonathan would be Mr Barlicek.
The tranquilizer used on the tiger in the classroom, Phencyclidine (PCP), brand name Sernyl was introduced as a human tranquilizer in 1953. but owing to adverse effects among human patients, it was withdrawn from the market in 1965 and relegated to a veterinary-only tranquilizer. However, PCP continued to cause unpredictable reactions among animal subjects. It also became popular among recreational drug users in the 1960s and 1970s as Angel Dust, and veterinarians found their offices and labs broken into by users looking for the drug. Thus, the use of PCP, or Sernyl, declined precipitously and generally was not used at all among vets by the mid-seventies. Therefore, a college veterinary program would not provide its instructors with PCP, a dangerous and disused tranquilizer, for its instructors. They certainly would not keep a dangerous drug in a classroom cabinet where Jonathan could steal it and shoot people with tranquilizer darts. PCP side effects include paranoia, dissociative delirium, hallucinations, and a myriad of unpleasant somatic symptoms. The physiological, chemical, and behavioral effects can be lethal in some cases.
When leaving West Berlin in the punk's van they are stopped at the DDR border crossing - the border guard is not wearing his regulation tunic belt with its distinctive silver hammer and compass buckle.
In the very end when Jonathan encounters the young woman that scolded him earlier and decides to shoot her in the derrière, the trajectory of the tranquilizer dart moves upwards in the final shot. However Jonathan is clearly aiming downwards, and the positioning of the characters also requires a downward trajectory.
When Jonathan returns to Los Angeles and first discovers the film that he inadvertently smuggled out of East Germany, it appears to be a canister of 35 mm film with an inch or two of film sticking out of the canister. Had the film already been used to photograph anything, it would not have had any film visible, as the camera would have been used to rewind all of the film back into the canister before the canister was removed from the camera. As presented in the movie, Jonathan appears to have smuggled an unused roll of film.