After getting hit in the face with a brick by the cow, Tina hoists the milkmaid's yoke onto her shoulders, and as she walks away, it can be seen that both pails must be less than three-quarters full (i.e., no milk can be seen in the pails). When she sets down the pails outside the house though, the pail on her right side splashes milk onto the ground even though it is barely tipped; it appears to be nearly full.
Near the beginning, when Willem uses his cane to strike at Ignatz on the table, the mouse "jumps" off the table onto the floor and runs away. However, from the way the rodent landed on the floor, it's apparent that it simply was dropped from above.
When Tina (dressed as Gretchen) throws the potted plant at Dennis's balcony and hits Caesar in the head, breaking the pot, the trajectory of the dirt and broken pot indicate that the "mess" will be only a foot or two behind Caesar. Dennis, who is sitting at the far side of the room, about 10 feet away, is hit by "shrapnel" that falls straight down on top of his head. Additionally, the pieces hitting Dennis are much too small and numerous to have come from the pot that hit Caesar.