MAJOR SPOILERS: New set updates and photos

Indeed, expected on the set were Matthew Fox (Jack), Evangeline Lilly (Kate), Josh Holloway (Sawyer) and Naveen Andrews (Sayid). But the first hardworking actor sighted was none other than Daniel Roebuck, who played the hapless (and previously detonated) Dr. Leslie Arzt.

The scene being filmed has been confirmed as not being either a flashback or dream sequence.

Looks like things pick up immediately after Juliet hits the bomb because the construction site looks like the Swan after it got sucked in. Jack, Kate, Sawyer, Miles, Jin were there. Saw Sawyer upset over Juliet's actions and runs toward the hole which is now stuffed with all the metal from the site. Also saw them and some stunt doubles clumb out of the hole using vines/rope.

Didn't see them filming, but saw Hurley and Sayid around set. Sayid's Dharma uniform was covered in a lot of blood so it looks like he's still hurt from last season.