These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Covered Up: Their cover of "Fire Woman" is generally assumed to be about Blaze the Cat. However, they are very quick to point out it's a cover and say that Blaze had nothing to do with the cover. Jun simply wanted a cover song on their 2009 album, and Johnny chose "Fire Woman"
Sonic Youth, which was a callback to multiple Sonic the Hedgehog songs.
Face of the Band: Jun Senoue actually stated that the band would cease to exist if either he or Johnny left.
Misattributed Song: They get this pretty bad. If its a vocal song in a Sonic game, they WILL get credited for it by someone. Some of the more confusing examples are Lazy Days ~ Livin In Paradise, and disturbingly, My Sweet Passion, which is sung by a girl. And perhaps the most prevalent songs to be hit by this are It Doesn't Matter and Escape From the City, being that they were bonus tracks on a Crush 40 album and share a guitarist.
Mondegreen: For the most part averted, but this hits hard in Knight of the Wind, which has these in the double digits.
For the lyrics of What I'm Made Of some sites will list lyrics in the chorus as "take a part of me" and others "take a bite of me".
Narm Charm: Being that most of their lyrics are made to be applicable to video games, this is kinda inevitable. Arguably hits its hardest in the song Sonic Heroes. If it wasn't for the rockin' music (and Johnny Gioeli's incredible singing), they'd be straight-up Narm.
Signature Song: Live and Learn, easily their most recognized and respected song from the series to the general audience.
Open Your Heart, their first song, also qualifies. Pretty much anything that includes Live and Learn will have this song as well.