Visible crew/equipment: When the man is hit in the face with a pie whilst having his picture taken, you can see a crew man's hand throw the pie directly in his face.
Continuity mistake: When Oliver tries to put the banana into Stan's hand, he puts it into his own hand and you can see the banana is facing right, but in the next shot the banana is now facing left.
Continuity mistake: When Charlie Hall slips on the banana skin with his tray of pies outside the pie shop, he places the tray on top of his left leg, but in the next shot the tray is under his leg.