Eric Idle and Chevy Chase became mutual friends after filming wrapped up. Shortly after the release of European Vacation, Idle and Chase began work on a screenplay for a follow-up called "National Lampoon's Australian Vacation." Aside from a few shark-related gags, neither could come up with much and the project was shelved.
Throughout all four Vacation movies, Ellen refers to Clark by the nickname "Sparky". In the DVD commentary for this movie, Chevy Chase mentions that the nickname was actually Beverly D'Angelo's idea, and she even affectionately calls him by that nickname in real life to this very day.
Chevy Chase mentions that after the release of the movie in theaters, he received dozens of letters from people who had visited London and claimed to have the same problem with the traffic circle where Clark cannot get left and is stuck driving in circles.
Dana Hill suffered from juvenile diabetes, which made shooting of Audrey's nightmare scene somewhat difficult. Dana had to be very careful to avoid actually swallowing any of the food she was supposed to be eating.
Clark can be seen wearing a t-shirt from "Walley World", the Griswolds' destination in the first film, National Lampoon's Vacation (1983), in the scene set in Chicago where he films Ellen in the shower. Later, while the family is in Paris, Rusty is wearing a "Walley World" sweatshirt in the restaurant scene.
The first time Clark hits Eric Idle's character with his car, Idle shrugs it off as being "Just a flesh wound." A similar remark is also made by the Black Knight after sustaining a serious injury in Monty Python and the Holy Grail (1975) also featuring Idle.
The "Pig In A Poke" game show host Kent Winkdale (played by John Astin) is a parody of two real-life game show hosts. The name "Kent Winkdale" is a parody of Wink Martindale - a notable game show host in the 70s and 80s (most notably as the host of The New Tic Tac Dough (1978)), and when he kisses Ellen and Audrey, it is a parody of Richard Dawson who often kissed the female contestants on Family Feud (1976).
In the DVD commentary, Chevy Chase mentions that (as of 2002) he still has in his possession several items from this movie, including the complete "Pig In A Poke" pig costume and the Walley World sweatshirt he wears throughout the movie.
In the closing credits montage, there is a painting of Clint Eastwood, which originally appeared on the movie poster (as well as VHS/DVD covers) from Pale Rider (1985), which was shown in theaters the same year as this movie.