Watch for Bonus platforms in any level. Jump onto them to fly to a special bonus area. Run through the maze, grabbing everything that isn't tacked down. You can play through the bonus areas as often as you like.

Crash Bandicoot: Warped instruction manual

Crash on a Bonus Platform

A Bonus Platform is a type platform in the Crash Bandicoot series. The platform has a question mark symbol to show it's a bonus platform. Once Crash hops aboard, it will take him to the bonus round of the level where he can collect Wumpa Fruit, crates, and extra lives. In most cases, the lives he collects will be added to his total amount of lives and the crates that he collects will add to the total of crates, meaning that in all levels that have a bonus platform in it, Crash must use it to get the clear gem for that level.

Also in the bonus round, if Crash falls off, is near an exploding TNT crate, or touches a nitro crate, he won't lose a life but he will lose everything he collects from that area. Crash then re-spawns before the platform, meaning he can replay it. However, once Crash completes a bonus area, he cannot go back into that specific bonus area even if he didn't touch the checkpoint after it. The only way is to re-enter that level. Bonus platforms are inaccessible when in time trial Mode. Note that if Crash has an Aku Aku mask when he falls off, he will lose the mask, although he won't lose a life.