Spongebob Squarepants - Another Doormat Mishap
In the episode where "The Strangler" was going to strangle Spongebob for telling on him, the strangler and Spongebob were outside the pineapple, while Spongebob was looking for his keys. There was no doormat by the door. After Spongebob said he would get the spare key from under his doormat. The camera switched to the door and the doormat was there with the key under it.