Revealing mistake: Carly, Sam and Shelby all corner Nevel in the ring. If you look in the corner where Shelby shows up, she's not in that corner until the light flashes on her.
Revealing mistake: During the shot where Chuck flips Spencer for a brief second you can see his face, which reveals that it's a stuntman as he is a different person.
Chosen answer: I don't know how to answer the first question but for your second question, there is going to be an episode after iPWV, called IDate Sam & Freddie which will deal with their kiss from iOMG. IParty with Victorious will not be related to IDate Sam & Freddie.
The I date Sam and Freddie proves that they are a couple.