When Joel is in his head and is visiting his session of the erasing process, no special effects were used to show the two Joels in the one scene. Jim Carrey had to take off his hat and jacket when he was not in shot and had to quickly sit down in the chair and visa-versa when he has to stand up.
Eternal Sunshine of the Spotless Mind (2004)
After filming, the remains of the full-size set were sold as scrap metal.
Both Kate Winslet and Leonardo DiCaprio learned how to dance the polka for the scenes set at the party in the third-class compartments.
In the scene where the water comes crashing into the Grand Staircase room, the film makers only had one shot at it because the entire set and furnishings were going to be destroyed in the shot.
Most of the ocean which extras were jumping into was 3 feet deep.
At $200 million, the movie cost more than the Titanic itself.