Doing the letter escape glitch, putting the letter in a taxi, and then moving to the corner makes you zoooom
Talking to this dude whilst on the house can softlock the game. (Normally works in the first 3 tries or so)
Ground pound rolling towards a wall when breaking a box can clip you through the wall.
Opening snapshot mode, the map, or the menu on a certain frame when uncapturing binoculars causes the UI (coins, compass, etc) to disappear. It reappears when you open another menu or capture anything.
Unloading one of the cutscene frogs after cappy lands on it makes the game crash.
Going through this corner in the Cap Kingdom let you just go through the wall, since the collision was too intricate. Patched in version 1.2