These two glitches are game changing and allow you to get sub 3 mins very easy. I demonstrate these glitches in video here:

For a text explanation, here's how you do it.

The flag borrowing glitch allows you take a flag from a level and take it to the next level. It is probably frame perfect so it's not easy to do (or guaranteed, but we will see in the future). To do that, when you end a level, a black screen transition executes (it has a star shape). In that transition, you can move your player and also pick up and drop a flag. So, if you are close enough to a flag at the end of a level, you can pick it up. To do the glitch, you have to drop the flag almost at the start of the next level. Since I'm not that good at doing that, I usually hold both "up" and "down" so that the player picks the flag and drops it continuously. If you master it, I'm sure you will get it more times than me ;)

The reset glitch is simple, and can be combined with the flag borrowing glitch to skip some levels. If you finish a level and rapidly reset, the level gets refreshed but the transition to the next level keep running. This way you can get closer to the flag and do the borrowing glitch. This is MOST IMPORTANT to skip the final boss.

Have fun ;)

Nuno137