The Customs and Immigration would not allow the visitors to enter the United States without the proof of return flights. The East Germans had only enough money together for two one-way flight to New York City as indicated at the travel agency in Berlin. Additionally, the agents would demand the financial proof that the visitors had adequate amount of money for travelling within the US before admitting them in.
The East Germans brought the small film projector with them to the United States. The projector would spin at half speed and the bulb at half illumination due to difference of voltage between East Germany (220 V at 50 Hz) and United States (110 V at 60 Hz). That is unless they brought the voltage converter along.
Trabant 601 S, the East German car driven across the Golden Gate Bridge, had SU sticker which was an international code for Soviet Union and three different vehicle registration numberplates: the correct East German one in the front along with archaic 1967 British numberplate (as denoted by "E"-suffix) and period-correct California numberplate. The vehicles registered in California are required to display California numberplates in front and rear to be legal; this Trabant didn't.
Terry Fator is shown as headlining at The Mirage in Las Vegas on the sign in the movie, but he didn't start there until 2009, 20 years after this movie was supposed to take place.
San Francisco isn't place where you can leave your knapsack and others in public without anyone stealing them right away. The East Germans left them on the bench in front of post office building while they ran over to the Golden Gate Bridge.
The Continental Airlines airplane flying overhead had the 1991-2011 livery and is 757 with blended wings, which weren't fitted to 757 until 2005 for -200 and 2009 for-300. The close-up of airplane landing on the runway is American Airlines 757 (also with blended wings).
The metal bench and city map signage in front of post office building in San Francisco are of 2000s design.
Lot of vehicles built in 1990s and later are shown in the background when the film supposedly took place in 1989 right after the fall of Berlin Wall.