Continuity mistake: When Thade takes the weapon from Leo the weapon is a futuristic laser type gun. When Thade is firing the weapon after being locked in the command centre, the gun is a stainless steel Beretta brigadier model. (01:50:00)
Revealing mistake: After the trained chimp is shot and is crawling into the cage, they show a shot of an ape turning around. You don't even have to look hard to see it but there's a two inch strip all the way down his face with no makeup. Clear as day. (01:41:30)
Answer: There were five different endings to the movie and late actor Michael Clarke Duncan saw them all. So far, no website seems to have all five endings. Just the one we're familiar with.