Continuity mistake: When Richard and Francoise are making love on the beach. They begin kissing deep under the water and continue all the way to the top. When they reach the surface they can stand up in the water which appears to be waist-level.
Continuity mistake: The photo that Richard downloads at the end is clearly not the one taken earlier. There are people in different positions, and one guy who was standing on the ground when the picture was taken is missing completely.
Continuity mistake: When they first get to the island and they are playing cricket, Keety is telling them all the rules of the game and asks "who doesn't understand?" Richard and Etiene raise their hands - when the angle changes, Richard's other hand is raised.
Continuity mistake: Daffy tears the screen between his room and Richard's to talk to him. The tears are different when Richard jumps up to talk back.
Chosen answer: In the alternate beginning, Richard is sitting in front of the large Buddha statue when a taxi driver stops and prompts him to take a ride with him. He explains that they celebrate New Year's by spraying each other with water guns, and gives one to Richard. While riding in the taxi, Richard sprays others and gets sprayed, having a lot of fun. It ends when Richard enters the "mall" where he will eventually meet the guy who offers him to drink the snake blood in the regular movie beginning. In the alternate ending, Sal turns the gun on herself and commits suicide. It ends by having a large ship rescue all of them when they're stranded at sea, banned from the island. The final words by Richard are something to the effect of "I have a lot of scars," which from what I recall is the actual ending of the novel by Alex Garland.