"Once Upon a Time" season 4 has officially begun production, and spoilers have surfaced regarding the premiere as well as a new cast member.

According to E! Online, Hans from Disney's "Frozen" will also join Anna, Elsa, and Kristoff for "Once Upon a Time" season 4. Georgina Haig has already begun filming as Elsa, while Elizabeth Lail will play Anna, and Scott Michael Foster will portray Kristoff.

Although we don't know who will play this "Once Upon a Time" season 4 character, spoilers confirm that Elizabeth Mitchell will join the cast as either the original Snow Queen, or Anna and Elsa's supposedly-dead mother.

Sadly, spoilers confirm that Olaf will not be joining "Once Upon a Time" season 4.

"It wouldn't fit, and it's so beautiful, his story in the movie," said co-creator Adam Horowitz. "The story we want to tell doesn't involve trying to expand upon that, nor do we think it should."

Meanwhile, the premiere date for "Once Upon a Time" season 4 has been confirmed to be September 28, and Adam Horowitz has revealed the title of the second episode—"White Out."

"Well, it's funny, we're not going to redo the movie, because we just don't feel like it's in anyone's interest for us to redo it," added Horowitz. "But what we are going to do, we're not ready to tell you. But what we can say is we're very aware of what we think makes this character from 'Frozen' so special and we want to honor that and make sure that what we do is in the universe of everyone fell in love with this past year."