'Breaking Bad' Star RJ Mitte -- VEGAS RAGER FOR 21ST BDAY ... Mom Was There Too

“Breaking Bad” star RJ Mitte rang in his 21st birthday by RAGING in Vegas -- with tons of hot chicks, tons of hard booze ... and his mother???

Mitte -- who plays Walter White Jr. on the AMC show -- hit up Ghostbar at the Palms Casino Resort this weekend ... where he partied hard with his BB co-star Daniel Moncada, “True Blood” actress Lindsey Haun and Amanda Fuller from “Last Man Standing."

... and his mom was there, too!

But parental supervision didn't keep Mitte from enjoying all that Vegas had to offer -- we're told the actor downed some Jack Daniel’s Tennessee Honey cocktails while cake fighting with some babes.

Hopefully RJ's night of boozing ended better than that time WW2 got drunk ...