Grey's Anatomy turns 300!

The ABC medical drama aired their 300th episode on Thursday night, in an hour paying tribute to several iconic moments from  its 14 seasons. 

An accident at a country fair brings in a variety of patients to Grey Sloan Memorial Hospital, several of whom look shockingly similar to original characters Cristina (Sandra Oh), George (T.R. Knight) and Izzie (Katherine Heigl) -- and even say "seriously," like the Fab Five did in early seasons. 

The original cast is also honored when a new class of interns is shown in the tunnel that the Fab Five previously called home, with “Glasses” even tripping like George did in the pilot when they get a page. The group then runs across the catwalk, as Meredith and Alex tell them to slow down -- which they were told to do in the pilot.

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Meredith is also seen riding a ferry boat in a tribute to her late husband, Derek Shepard (Patrick Dempsey), and the episode's opening scene ended with the show's original theme song, "Cosy in the Rocket,” by Psapp.

ET's Leanne Aguilera was with the cast of Grey's Anatomy as they celebrated their milestone episode at TAO in Los Angeles on Saturday. 

"I mean, 300 episodes, I can't believe it," Caterina Scorsone, who first appeared in the series in season seven, marveled. "I remember when we were doing 250, and we were like, 'What?!'" 

"When I first joined the show in season five, [I was a] Scottish actor straight from Scotland and they [had] just celebrated the 100th episode. At the time, I was like, 'How does anybody ever get to 100 episodes?'" Kevin McKidd added.

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Original cast member Chandra Wilson, meanwhile, said she could never have anticipated the show lasting as long as it has. 

"I don't even know [how long the show will go on]," she confessed. "I said, 'Two years,' I'm sure. So, here we are." 

And Grey's creator Shonda Rhimes doesn't see any reason to wrap up the long-running series. 

"[Ellen Pompeo and I] have a deal," she revealed. "We're going to do it as long as the other one is in, and if the other one is not, then it can't happen." 

Grey's Anatomy airs Thursdays at 8 p.m. ET/PT on ABC.