Barry is trapped in the speed force as an old enemy returns in an all-new Kevin Smith-directed episode of The Flash!

Tonight’s the night! The much-anticipated episode of The Flash from director Kevin Smith (Mallrats, Zack and Miri Make a Porno, Tusk) will finally hit the airwaves this evening, and The CW is letting out all the stops to get us ready.

Photos: Image Gallery for The Flash 4×21 – “The Runaway Dinosaur”

Up first is a brand-new extended trailer for the episode (above), featuring a ton of behind-the-scenes footage of Smith on set. The CW is really promoting the fact that Smith is behind the camera on tonight’s episode, but it’s also exciting to remember who wrote “The Runaway Dinosaur” — Zack Stentz, who was responsible for the first Thor movie and X-Men: First Class (alongside writing partner Ashley Edward Miller).

The CW has also released three new clips from tonight’s episode. The first scene appears to pick up immediately after last week’s episode ended, with Dr. Wells, Henry, Joe, Iris, and Cisco staring in disbelief at Barry’s apparent “death”:

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The second clip is the same scene that was previewed earlier this week in comic book form. It features Iris and Cisco in the S.T.A.R. Labs morgue, searching for Eobard Thawne’s file on Barry when they’re interrupted by the return of a long-dead foe:

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The last clip is a exclusive, featuring Barry having a conversation with Joe — only it isn’t Joe, it’s the speed force itself(!):

In addition to all the new footage, The CW has also released an epic new poster for tonight’s episode:

Official poster for The Flash episode 4x21 - "The Runaway Dinosaur." (Image Credit: The CW)
Official poster for The Flash episode 4×21 – “The Runaway Dinosaur.” (Image Credit: The CW)

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Are you hyped up yet? Okay, here’s the official episode synopsis for “The Runaway Dinosaur,” in case you’ve forgotten:

KEVIN SMITH DIRECTS – With Barry (Grant Gustin) gone, the team must figure out a way to handle the return of an old enemy – Girder (guest star Greg Finley).  Realizing Girder is retracing his steps from his last attack, Iris (Candice Patton) volunteers to act as bait to trap him in S.T.A.R. Labs.  Meanwhile, Barry fights to return to his old life.

The Flash airs tonight at 8/7c on The CW. We’ll be live-tweeting during the episode and we’ll bring you a full recap tomorrow morning, so be sure to follow us on Twitter, Tumblr, and Facebook for the very latest!