Air Crash: Secret Level Warp
In "Air Crash," the seventh level of "Crash Bandicoot 2: Cortex Strikes Back," you will see an area with some boxes that are floating in the water next to the place where you get into the vehicle. Ignore the vehicle, jump onto these boxes and leap onto the platform. You will instantly be transported to a secret area in the "Snow Go" level. In this snow-themed area, you can collect a large selection of apples and defeat penguin enemies.
Unbearable: Bonus Level
Get on the bear in the 15th level of the game, "Unbearable," and ride it until the animal throws you to the ground. Perform a long jump back over the chasm and head to the place where you first encountered the bear. As soon as you get there, you will teleport to a secret warp room that takes you to a secret level called "Totally Bear." In this level, you'll ride on a bear's back through an ice canyon, avoiding enemies and collecting apples.
Diggin' It: Teleporting Platform
Play the 17th level, "Diggin' It," until you encounter a plant that spits seeds and is sitting on a platform. Perform a belly flop jump and land on the plant. You will disappear and then reappear in a warp room that takes you to a hidden part of the "Road to Ruin" level. This Aztec-themed area is full of boxes that you can smash open to reveal prizes. Make sure that you avoid the rats.
Boss Fight Rematch
Return to the warp room of a boss that you have previously defeated. Stand on the platform in the middle of the room and press "L1," "R1," "L2," "R2" and "Triangle" at the same time. When Crash points upwards, press the "Up" button. You will once again fight the boss of the warp room.
Other Secrets
When you're playing the "Unbearable" level, the polar bear that is chasing you will fall into a hole. Jump down after it and you'll end up in a bonus area. This underground jungle cave-themed area has many boxes to smash and lots of apples to collect. When you see a polar bear in the second world, jump on it to get an extra life. Continue jumping to get more lives. Skipping cutscenes generally means that you'll get to play the game quicker, but if you skip the very first cutscene of the game, you'll skip the entire first level. You'll start the level off in the warp room.