The logo of American Express used in the 1975 hotel scene is a modern Version, rather than the actual one used in the time setting.
In the club in 1976 the song "Yes Sir, I Can Boogie" by Baccara is played. The song came out in 1977.
"Congratulations" in Czech mean "gratulace" or "gratuluji", not "Gratulame", as said in the movie.