When Mario arrives, Lucas is not wearing a nose/septum ring, nor is he wearing one as he shows Mario the bedroom... but when they then go into the bathroom, Lucas is wearing a septum ring, which has gone again while Lucas sits in the living room and Mario is singing in the shower.
Lucas's septum ring then reappears a few minutes later when the guys are sitting in the kitchen eating chicken.
When Lucas is playing a semi-classical piece (Prayers for Alicia by Timothy Lewis) around 29:40, after Mario has shown him one of his drawings, there is no DC power adaptor plugged into the keyboard (right-most connector on the back). By the end of playing the piece, the DC power adaptor is now plugged in.