At the beginning of the tailor scene, when Raven sews her sleeve to the 'sewing machine' she actually sewed it to the blue shirt (the one she was trying to return). But when she frees her arm, neither her shirt or the blue shirt have stitches or tears. They look brand new.
During the tailor scene (when Raven is pretending to be the tailor) and Frank comes in after being splattered with coffee and whipped cream, we see him in the mirror and there is a bright white whipped cream spot. Then he wipes it off and the spot is dark gray. Then when he turns around it's bright white again, as if he never wiped it.
At the beginning of the episode, Raven is looking for a note from her maths teacher in her bag and pulls out an iron which is unplugged. When she finally finds the note the iron is plugged and she uses it to straighten the note out. When she gives it to her dad, the iron is unplugged again.