When the boys are concocting their "prescription", the level of liquid in the beaker varies from shot to shot.
When Curley gets knocked backwards at the dining table by Moe, the two male servants come to help the matron and him. The next second, one of those two servants is seen standing at the entrance receiving the lord of the manor.
Moe is trapped, face down, under the pre-hung door after it falls on him. Curly uses an electric saw to try to cut him free. But he cuts too far and saws through the floor, send Moe and the debris crashing to the floor below. When the scene cuts to Moe and the mess, Moe is face up.
While the dining room appears awash in foam after the keg explodes, in the background, extras are simply poking their heads through white sheets.