Marilyn Manson, also a native of Canton, is subject of their song "My Girlfriend" although they are not acquainted.

Besides playing for Relient K, Hoopes has also done backup vocals for certain Matthew Thiessen and the Earthquakes songs, and has been a guest guitarist at concerts for the band My Red Hot Nightmare.

For several months in 2010, Matt Hoopes did not travel with Relient K. However, he remained very active as a team member and band-mate.

In 2019, Hoopes launched a guitar effect pedal brand named "1981 Inventions".

[3] Their first product was the DRV pedal, designed by engineer Jon Ashley of Bondi Effects and based on the ProCo Rat.