PREVIOUS, 11:43 AM: At the Once Upon A Time Comic-Con panel this morning, series executive producers Adam Horowitz and Edward Kitsis showed a clip from the Season 4 premiere, where the Evil Queen (Lana Parrilla) enters a hospital, goes to a holding cell, and demands that her Mirror (Giancarlo Esposito) return.  It was announced earlier in the month that Esposito was returning to the show. The executive producers mentioned that they are still working on the season premiere. Also shown from the premiere was a clip with Frozen characters Elsa and Anna (Georgina Haig and Elizabeth Lail, respectively) leaving flowers at the grave of their parents. Of course, the crowd here in Ballroom 20 went absolutely nuts.

ABC also revealed the Season 4 trailer. Check it out:

Whether there will ever be a musical version of Once Upon A Time, Kitsis said, “Problem with doing a musical, is we don’t know how.”

ABC's "Once Upon A Time" Panel - Comic-Con International 2014Another key highlight at the panel was a short clip in which Horowitz and Kitsis hold a minicamp for the writers on the Disney lot to brainstorm fairy tale characters for Season 4. Most of the writers treat the minicamp like real camp, i.e. writer Jane Espenson brings marshmallows and a stick, while others brought a life vest and a canoe paddle. When the group gets writers block, Horowitz calls up his Lost mentor Carlton Cuse on the red ABC's "Once Upon A Time" Panel - Comic-Con International 2014phone, who refuses to pick up. After the writers’ room rejects the idea that the Disney theme park villain Frank Matterhorn should be the Season 4 villain, a pizza delivery guy arrives and suggests that the writers should focus on Frozen.

Ginnifer Goodwin (Snow White) dialed in via Skype, apologizing to fans in Ballroom 20 for her absence. At the end of the video, Goodwin walloped actor Michael Socha (who played the knave from Once Upon A Time In Wonderland) with a club. He joins the cast this season.