Moon clip
A moon clip is a type of out-of-bounds clip that involves attaining skew at the moment Mario collects a Power Moon, so that the animation of collecting the moon forces Mario upright at the position of his feet, thus forcing him through an adjacent wall or ceiling. The Power Moon used for the clip must be uncollected, meaning that a player will only have one attempt to perform a moon clip unless they create a backup of their save file.
Execution
To perform a moon clip, one will need to execute a backflip while facing away from the wall, and cancel the backflip animation by performing a cap throw toward the wall just as Mario collects the Power Moon. Mario's hitbox tilts sideways when he performs a cap throw during a backflip in this manner, and collecting the moon forces his hitbox upright. However, if his hitbox is tilted into a wall, Mario will be half-bounds after he is forced upright, allowing him to be moved fully out of bounds after the moon cutscene is over.
Examples
There are a few notable moon clips that have been made applicable for speedrunning:
Each of these clips requires a slightly different timing for the inputs, since the moon positioning and timing is different for each.