3.In order for Lindsay Lohan to play both Hallie and Annie, each scene was filmed twice — Lindsay would film one part with a stand-in, then they would re-stage the scene and she would play the other twin.
4.After filming the first take, Lindsay was given an ear piece so she could hear the dialogue she previously recorded as the other twin.
5.Hallie and Annie are named after director Nancy Meyers' and producer Charles Shyer's children.
6.The real Hallie and Annie have small roles in The Parent Trap — Hallie played a camper named Lindsay and Annie was the woman who brought Elizabeth the first aid kit.
7.The Vampire Diaries star Kat Graham appeared in the movie as Jackie, one of Annie's friends at camp — she originally had a speaking role, but her scenes were cut.
8.Also, Kat still has the original Camp Walden shirt that she wore in the film.
9.The memorable scene when the lizard is on Meredith's head consisted of a real lizard, a toy lizard, and a CGI lizard.
10.Chessy is named after a decorator who was a friend of Nancy Meyers — even Lisa Ann Walter thought she was playing someone named "Jessie" when she first got the role.
11.Also, three years after they filmed the movie, Lisa Ann Walter coincidentally had identical twin boys who were born on Oct. 11, the same day as Hallie and Annie.
12.Vera Wang actually designed the wedding dresses that were seen at Elizabeth's store in London.
13.Joanna Barnes, who played Vicki, was Vicky Robinson, the evil girlfriend, in the original Parent Trap movie.
14.Simon Kunz, who played Martin, originally auditioned to play a wedding photographer who had one line in the entire film.
15.Simon and Lindsay came up with Annie and Martin's signature handshake themselves — it took "two or three hours" to create and learn the entire routine.
16.Real chocolate was actually dumped on Polly Holliday and Maggie Wheeler during the scene where Marva Sr. and Marva Jr. investigate Annie's cabin.
17.Also, while driving between the set and showers, the chocolate actually hardened on Polly and Maggie, which made it harder to get off.
18.During the scene where the water balloon pops on Annie's head, a small needle was hidden in her hair to increase the chances of the balloon popping.
19.When Hallie meets Meredith outside the elevator, she sings part of "Let's Get Together," which is from the original Parent Trap.
20.The emotional scene when Chessy realizes that it's actually Annie and not Hallie took 73 takes to get just right and was filmed over several days.
21.Lindsay's brother Michael played the young boy who accidentally gets sent to Camp Walden thinking it was an all-boys summer camp.
22.Also, you can spot Lindsay's mom and her other siblings during the scene where Hallie arrives at the London airport as Annie.
23.And finally, there was originally a scene where Hallie as Annie meets Queen Elizabeth II after stopping to see Buckingham Palace.
You watch The Parent Trap (and the original version) on Disney+ now!