Considering how close it'd be to the Winter Event, I wouldn't bet on it, but if we do....
I hope the Fek'lhri award ships get transferred to the Halloween Event. While it's nice to have a new set of ships available for the Winter Event, I can't see another kind of ship that would be more appropriate (scare-wise) than a ship that belches fire and smoke.
Considering The Twillight Zone's a CBS show, any chance of at least having some nods to classic The Twillight Zone TV episodes?
I'd like to see the computer generated Fear Clown from Voyager make an appearance (whether as a host, or a threat, it doesn't matter, maybe both?).
I miss the old door-to-door aspect of City of Heroes' Trick-or-Treat system. Maybe a holodeck simulation of 21st town that could fit the bill, with STO creatures popping out of doors (such as the flying parasites from TOS, Mugatos, etc). To be honest, it would be nice non-tradeable Lockbox keys would be the top treat (rare enough that doesn't TRIBBLE up the Exchange thing, but common enough not to cause people who don't have the lobes for trading/exchanging to tear their hair out trying to work off their lockbox collection).
Smoke machine type fog would make a great ground cover. Maybe with an occasional eyestalk popping up....