Mrs. Little starts the washing machine without adding detergent. It's possible that there was already detergent in the machine (since it's a front loader), but when we see Stuart in the machine for the next few minutes, the water is clear enough to be rinse water (without detergent).
At the time when Uncle Crenshaw asks for his favorite "Little" nephew at the family gathering, Grandpa Spencer is not in the group shot. After switching shots and going back to the group shot, Grandpa Spencer is there.
When George and Stuart are asked to leave the room while the Littles and Stouts talk, George picks Stuart up in his palm and Stuart's tail hangs over the edge of George's hand. When they show the two walking out of the room, Stuart's tail is now underneath his butt and not hanging.
No front load washing machine would fill in the manner depicted. First, the water level would never be as high as it is shown, especially with such a small load. The washer would be partially full. Second, the water spigot would not be in the rear of the machine, let alone mounted on the drum. It would be either above the door or in the area around the drum, but not mounted on it. Third, once started, the machine would most likely tumble while filling, or at least do some tumbling before "deciding" on a load size (and thus, "deciding" on how much to fill, how much time it will take, etc.). This machine appears to behave more like a top loader, in that it fills completely and then washes.