When Margot and Royal are watching the Peter Bradley Show together in Ritchie's room, the door to the hallway is clearly open. However, when Ritchie enters the room from the hallway, he has to open the (now fully closed) door.
In the tent, Margot places the phonograph needle in the middle of one side of The Rolling Stones album. However, when the song ends, the needle is shown at the end of the first track.
When Kumar and Royal are in the game closet, there is an shot of one of the Dalmatian mice running across a shelf filled with games. The games in this shot are arranged in a completely different order than in the rest of the scene (and the previous game closet scene).
When Royal and Pagoda first meet in front of the hot-dog stand, the blind man with a dog sitting on a bench behind them has sunglasses in one shot and no sunglasses in the next.
Royal's cigarette jumps from his hand to the ashtray repeatedly when he is having a conference with his three children.
Artist Elliott Puckette's name is badly misspelled in the credits (her paintings appear in the film).
After Royal has Etheline sign papers, the notary is supposed to stamp them, but it is visibly obvious that the notary is just lifting his stamp up to the papers but not actually pressing down or stamping anything.
During the tent scene, a The Rolling Stones record is playing. The two songs played consecutively are "She Smiled Sweetly" and "Ruby Tuesday". It is clear that no tracks are skipped. Although both songs are on the Rolling Stones' album "Between the Buttons", these songs have never appeared consecutively on any Stones' release.
Despite having just attempted suicide, which should have put him under constant observation, Richie is somehow able to check himself out of the hospital.
When Margot is on the roof with Richie and Mordecai, she lights two cigarettes in her mouth but when she takes them out, a piece of paper remains between her lips; she pretends nothing has happened and in a few seconds she manages to remove it smoothly.
In the beginning of the film, when we are introduced to Margot Tenenbaum, the narrator states that she was 12 years old when she first ran away, and that she ran away a second time 4 years later, when she lost half a finger, making her 16 years old at the time. Later in the film when Margot is telling the story of her lost finger to her nephews, she states that she was only 14 years old when she had run away.
In the chapter 2 introduction, it says on the pages,"Uzi is on the steps with a duffel bag over his shoulders..." when Ari is at the door holding Buckley, without a bag over his shoulders.
It's said that Mordechai's feathers have gone white due to stress. The misconception that stress turns human hair white is because stress can kill off living follicles, so that the darker hair falls out leaving just the white hairs behind. It's probably different for birds.