In the episode "Who did it to Trina?", it was acknowledged that Drake & Josh is just a television show in Victorious. In the preceding episode titled "Helen Back Again", there were characters present and mentioned in the episode that are from Drake & Josh and the episode acknowledged that Drake & Josh is in the same world as Victorious.
When Trina and Robbie are in the play, Trina's lipstick goes from being on in one shot, then completely disappears and then is back on again.