Back in NJPW, Finn Balor - or Prince Devitt as he was known then - founded a group called The Bullet Club, who have since gone on to become arguably the most popular stable in pro-wrestling. When Finn arrived on Raw, however, WWE decided to riff on the name and establish "The Balor Club", which now includes Gallows and Anderson.
They're obviously very similar, and a bit of confusion is inevitable... just ask Corey Graves!
Last night on Raw, the announcer mistakenly referenced the Bullet Club as Finn was making his entrance.
This probably doesn't seem like a big deal (and it isn't), but Vince McMahon is notoriously crotchety about other promotions or groups being mentioned on WWE TV, so Graves might have got a bit of an ear-bashing over the mix-up.