When I first saw tonight's "It's Always Sunny in Philadelphia," I instantly had questions for the episode's director, Matt Shakman, about how they pulled off the various technical challenges involved in "Charlie Work." He was kind enough to provide a detailed explanation, coming up just as soon as I bang the stool on the floor three more times...

So how did Shakman and the "Sunny" crew create the illusion of one continuous take for "Charlie Work," given that the bar interior and exterior are in different places? And was the whole thing just an elaborate tribute to "Birdman"? Shakman explains all:

The exterior of the bar is an old warehouse in downtown LA, so any time we transition between the interior bar and the front, it's a visual effect.  When they meet the delivery guy outside for instance, the background of the bar that is visible through the doorway is a VFX plate.  Sometimes I used the front door as a transition (following Charlie out at the end for example, or when he first brings the inspector inside the bar), where we match cut the inside of the door on stage with the door on the exterior set downtown.  
The sets on stage are only one level, so every time we go to the basement, there is a camera trick.  Some are simple--where we pan past the brick wall and hide the cut or go through a pool of darkness--or where we are more ambitious and use green screen (coming back into the bar from the basement for instance was a blend of a shot that panned into a green screen with a shot of the keg room that continued the motion).
The stage sets that are contiguous are the bathroom, main pub interior, back office, and keg room.  The bathroom wasn't originally connected but we made it connect for this episode. For this episode we also built a partial back alley on stage.  There's a back alley location in downtown LA that we usually go to.  We used the real downtown location for when the delivery guy is first seated and Charlie sees Devito running away.  I wanted that to be the actual place so the audience wouldn't doubt the veracity when we used the stage set for later scenes: Charlie arguing with dee about moving the dumpster and checking in with the inspector in the alley.  Going from the interior bar set to the real alley required some green screen and a few camera tricks--going into a wall as Charlie passes, and then coming off the wall on location to reveal the real exterior alley, etc.
BUT there is a huge chunk of the show that is one take, no tricks (about a third). It begins with Charlie first escorting the inspector inside the bar and continuing all the way through to Charlie leading the inspector to the basement.  It was rehearsed at the end of a Tuesday if I remember.  Took about two hours to stage it all.  Actors then went home to study up on lines and I took the crew through the camera blocking.
The next morning we took about four hours to light everything and rehearse the camera move again and again.  Our B camera operator wore a headset and talked the A camera operator through the choreography during the shot.  Reminding him what was next, who to focus on, where the next transition was, etc.  The AD's practiced (with a bunch of PA's and set dressers) moving all the live chickens in and out of the back office in a very short amount of time.  And we worked out all the other miscellaneous things--Devito's black paint, the chickens that shuttled back and forth to the keg room, etc.  Then we brought in the actors and started shooting.  Took about twelve takes if I remember right.  Around 11 script pages.  A third of the show.  All before lunch.  
And there is another section that runs for a bit--from Charlie turning on the power breaker, through bringing the delivery guy to the back alley.  That's a solid chunk too without camera trickery.  
We spoke to FX early on about commercials.  There are a few breaks in the first half.  But once Charlie flips on the breakers to bring the light back, there are no more commercials. 
(Also), the Jazz score written by Cormac Bluestone (who also wrote "The Nightman Cometh") came before any of us saw "Birdman." So our continuous take "Sunny" episode became an unintended homage to that film.

What did everybody think of "Charlie Work"? And how are you feeling about ol' reliable "Sunny" at this point of season 10?

Alan Sepinwall may be reached at sepinwall@hitfix.com

Alan Sepinwall has been reviewing television since the mid-'90s, first for Tony Soprano's hometown paper, The Star-Ledger, and now for HitFix. His new book, "TV (The Book)" about the 100 greatest shows of all time, is available now. He can be reached at sepinwall@hitfix.com