They had this to say about Zef:
"Zac Efron, Corbin Bleu, Ryne Sanborn and Chris Warren were also on hand, shooting classroom scenes. Though all the actors had their own well-guarded trailers, the guys tended to hang out on set and chat with extras and crew."
A poster on IMDB also met Zac on set and said he was hotter in person (duh!) "and he was sooo nice and surprisingly normal."
Obligatory hot picture: