FAQ

No. A single press release from Warner Bros. attached Ronald Reagan and Ann Sheridan to the project, but it was likely just a filler piece, designed to keep studio contract players in the press. On that basis, it has become an oft-repeated trivia piece, but there was no basis to it. For a longer discussion, see here.

For the plot of the movie, they're specialized documents that allow the bearer to travel anywhere in the world, including from Nazi-occupied countries. The letters are actually a "MacGuffin" - a term director Alfred Hitchcock and writer Angus MacPhail coined to describe a plot point that is deliberately left vague so as not to draw too much emphasis away from the real story but still is a driving factor in propelling the story itself. The letters themselves are entirely fictional.

Yes. In Hungarian, 'sz' is pronounced as an 's' as in 'lasso' and not with a 'z' sound. The character is from Czechoslovakia (now two independent countries, Czechia or the Czech Republic and Slovakia). Before WWI and the Treaty of Trianon, there was no such country as Czechoslovakia, as it was part of the Austro-Hungarian Empire. In fact, the very name itself, 'Laszlo', is a quintessentially Hungarian (Magyar) name: Saint Lászlo was the third king of Hungary, from 1077 to 1095 (under a constitutional monarchy established in 1000 AD).