Nature Pants / Opposite Day - S1-E9
Continuity mistake: When Spongebob goes to answer his door, Patrick was obviously in front of the door. After Patrick says, "Spongebob doesn't like me anymore", it cuts to a different shot to show the outside of the front door, and Patrick has moved to the side of the door.
Nature Pants / Opposite Day - S1-E9
Continuity mistake: Opposite Day: The front door knob on Squidward's house repeatedly switches between the left and right side of the door, so it opens the opposite way (it has nothing to do with it being opposite day).
Nature Pants / Opposite Day - S1-E9
Continuity mistake: In "Opposite Day", Spongebob pushes Squidward through the sand, leaving a pile of sand. Two shots later, they are now on Spongebob's sidewalk and the sand pile has disappeared.
Nature Pants / Opposite Day - S1-E9
Continuity mistake: In most of the show, Squidward's house only has windows on the front of his house. But, in "Opposite Day", he has windows on the "ears" of his house, which don't appear throughout the show.
Nature Pants / Opposite Day - S1-E9
Continuity mistake: In "Nature Pants", Spongebob comes back home, where his friends have thrown a "Welcome Back" party for him. When he enters, two balloons float behind him. In the next shot, they disappear.
