I found this particular slip-up in the episode "Secret Box". At the point where Spongebob is in his room pondering about Patrick's secret box, his house is shown from the outside and his bedroom light is on. When it shows his room from the inside, however, the light is off. This is not only true for that one particular moment, but it repeats this pattern throughout the entire scene! I can't even think of a reasonable explanation for that except that the window is magic.