'Castle' Season 6 Finale Spoilers: Stana Katic as Kit Kat, Nathan Fillion Live Tweets with Eddie McClintock [Watch Promo Video]

  @jotfields on May 13 2014 2:49 AM
Stana Katic is Kate Beckett in the ABC series Castle; Season 7 Premieres September 2014
Stana Katic poses with the award she won for favorite dramatic TV actress for her role in the series "Castle" at the 2014 People's Choice Awards in Los Angeles, California January 8, 2014.

"Castle" Season 6, Episode 23, the season finale titled "For Better or Worse," airs May 12 on ABC. Stana Katic's Kate Beckett checks in with someone who called her "Kit Kat." Stana has been on Twitter break since filming wrapped up in April. Still, Caskett fans will have Nathan Fillion live on the SNS during the 6x23 East Coast broadcast.

Spoiler alert: This feature contains spoilers on the Castle Season 6 Finale. Read at your own risk.

Eddie McClintock of Syfy's "Warehouse 13" joins Nathan Fillion on the aforementioned Twitter Live Tweet. McClintock guest stars on Castle Season 6, Episode 23 as Rogan O'Leary. In one of her tweets, Stana teased that Eddie will be "causing trouble."

In a comedic twist on the Castle Season 6 finale, Rick Castle (Fillion) and Kate Beckett (Katic) both learn that Kate got married in Vegas 15 years ago. Beckett does not remember any wedding. Castle wants to know the guy she married.

Getting married in Vegas is something a young Kate Beckett would do. In various times throughout the series, Beckett has hinted there definitely was mischief in her youth. Still, the plot might not be plausible for all the viewers. Watch the Castle 6x23 preview on YouTube or play the video below.

"The only thing I'm not excited about," says Kate Beckett, "is having to say my vows in front of those people." Captain Gates joins the conversation to say something sweet.

Little is known about the "trouble" that Eddie McClintock may bring. Castle Season 6, Episode 22, aka the fall of Senator Bracken, was a rather heavy penultimate show. The finale could be a lighter Caskett wedding story. Or so some fans hope. However, Stana did say this on Twitter:

"[Castle Season 6] finale had us saying goodbye to a number of colleagues today." (See the tweet below.)

The reactions on Twitter cover many possibilities. Viewers should be able to decode the message after watching the Castle Season 6 finale.

WATCH: Kate Talks About Wedding Vows in Castle Season 6, Episode 23 Sneak Preview | ABC on YouTube

Castle Season 7 is officially on, as confirmed by ABC. Rick Castle and Kate Beckett are expected to return in the fall programming. Fans can also watch the Castle Season 6 finale anytime on Watch ABC and ABC On Demand.

Stana Katic's Cryptic 'Goodbye'

Nathan Fillion to Live Tweet Commentary on the Castle 6 Finale (with Eddie McClintock)

More TV Guide and Spoiler Features

'Castle' Season 6 Spoilers: Stana Katic, Nathan Fillion in Big 'Bracken' Episode; Finale Airs May 12, Season 7 Happening? [Watch Promo Video] 'Revenge' Season 3 Finale Spoilers: 'Major' Characters Die, Victoria Grayson Finds the Truth; Season 4 Clues and Questions Expected [Watch Promo Video]

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