Continuity mistake: I know that Animators re-use backgrounds but it is painfully obvious that when Keitaro and Narusegawa are leaving the exam results posting they walk in a straight line past the same "Ristorante" three times.
The Perfect Thanksgiving - S2-E6
Continuity mistake: The hospital where Nurse Kathy works isn't the same one she worked at in "Episode Eleven" and "The Test".
Snow Place to Go/Dunce Upon a Time/Gems the Breaks - S2-E4
Continuity mistake: Snow Place to Go: Toothy pulls half of Cuddles' body out of the hole in the ice, and some of its blood is next to the hole. Then when Toothy looks down at the orca's eye through the hole, the blood is gone, and in the next shot, Cuddles' corpse is gone completely. (00:04:32)
...And Spaghetti Sauce - S1-E4
Continuity mistake: When Laura comes to the pub and has sex with one of the guys, she spots the (hidden) video camera at the bar. One moment, it is entirely covered with a cloth. The camera angle changes and it is partly uncovered.
Jane and the Truth Snake - S2-E5
Continuity mistake: When we first see the guys at the pub, Jeff takes a swig of beer and you can see that his glass is almost empty. After a few seconds of conversation, he takes another sip and the amount of drink has significantly increased. (00:06:00)