The idiomatic expression "small appearance" means that something or someone appears to be insignificant, unimportant, or not worth much attention. Full definition
Koopa Paratroopas make small appearances in several of 9 - Volt's classic Nintendo - themed microgames in the WarioWare series. (mariowiki.com)
Pauline makes small appearances in the Nintendo Monopoly and Donkey Kong Jenga board games. (mariowiki.com)
Here, both of them make a very small appearance as they try to keep Mario and Yoshi from infiltrating Bowser's Castle or stop Mario from getting a feather. (mariowiki.com)