Nintendo games are fascinating for the things they hide, and Super Mario Galaxy is no exception. For instance, did you know the opening scene wasn't actually in space, but a floating image in the Mushroom Kingdom?
Super Mario Galaxy was one of the first games ever covered by Off Camera Secrets, so the channel decided to return to Galaxy to everything they didn't show off the first time around.
Some of those include the fact that Princess Peach's castle doesn't have a garden out back, Bowser Jr having a fully modelled back like his dad, and Koopa shells look real creepy inside:
Eww. For more into the areas of Super Mario Galaxy that Nintendo didn't traditionally let you see, the full Off Camera Secrets episode is embedded below.