Here is the full list of all 10 Spoiler Alert achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Get gold star score in all 10 levels in the Mariachi World.
Watch the credits from finish to start.
Do the leap of faith in World 3, level 12 - without middle landing on the support block.
Uncomplete the main game.
Get gold star score in all 90 main levels.
Find all 3 hidden main treasures.
Unlock all 3 main worlds.
Get squished flat as a tortilla.
Jump more than 150 times.
Cause more than 10 time paradoxes.