Muller currently plays the roles of:
- A Village Kid in Samurai 3 (The Interactive Adventure)
- Big Vinny Guard (The Interactive Adventure)
- He is the younger brother of Christopher Anthony Muller
- Mario's house in series is actually the Muller house
- He is seen going through puberty throughout the series, this is lampshaded in series and even contributes to Ness's slight changes in personality as the series goes on; such as being willing to engage in witty banter and becoming more sarcastic, while when he was younger, he was very serious.