Squidward's bed is smaller than in other episodes.
In the scene where SpongeBob and Patrick enter Squidward's house, in some shots Squidward's upper lip is defined when it shouldn't be.
When Patrick shines a light under Squidward's hot water bottle, SpongeBob's hands as they appear ungloved are visible underneath. SpongeBob's gloves should be showing up in the silhouette.
When SpongeBob and Patrick enter Squidward's house in "Sandy's Rocket", Patrick complains about the smell of Squidward's "egg sack". However, in "Something Smells", Patrick doesn't smell SpongeBob's breath because he doesn't have a nose.
When Spongebob walks to Sandy's house you can clearly see that there is a ladder on the platform. In the next scene it is gone.