Fun Fact: The Pikmin 1 bad Ending has slight differences according to which Area you decide to have your last Day in and which Onions you have found before taking off. Coming down to 10 Different Versions from just the bad Ending alone.
Basically, Olimar makes it off the planet, but notices the creature like snuck on the ship because he was loyal and ended up suffocating, and Olimar panicked and reversed the ship which resulted in the crash (as opposed to an incomplete ship). This is still the good ending because he otherwise completed his goal, but he unfortunately still needs to be a Leafling.