Scenes from Oldboy are still fresh in my mind. Here's some trivia, thanks to IMDB.

• Based on Japanese Manga "Oldboy" by Minegishi Nobuaki and Tsuchiya Garon.
  
• Four live octopuses were eaten for the scene with Dae-su in the sushi bar, a scene which provoked some controversy abroad. When the film won the Grand Prix at Cannes, the director thanked the octopus along with the cast and crew.
  
• Choi Min-sik trained for six weeks and lost twenty pounds to get in shape for the role of Dae-su, and did all of his own stuntwork.
  
• The telephone number (08-6600330) which is supposed to go to Oh Dae-su's daughter's foster parents home in Sweden, actually has been "shut down requested by the owner of the number" (that's what the voice says when you call the number). But you are referred to another number (08-54589400) which goes to "The Embassy of the republic of Korea" in Stockholm, Sweden.
  
• The famous one-take corridor scene was shot in three days.
  

Official Cannes site on Oldboy.

Another review, from Nixflix here.

I can't find the official Korean website, so the Japanese one will have to do.

The Oldboy Ultimate Edition DVD set comes in an all-copper case. Pretty! (but not worth the price tag imho.)