[s5e22] What A Difference A Day Makes -

: To promote the 100th episode, ABC created a real wedding website for Meredith and Derek that fans could actually visit and RSVP to.

: Jeffrey Dean Morgan makes a final appearance as Denny Duquette, appearing as a hallucination to Izzie that Derek and Bailey eventually realize is a symptom of her worsening condition. Behind the Scenes Facts [S5E22] What a Difference a Day Makes

: As a wedding gift, Derek gives Meredith her first solo surgery—a successful colon surgery overseen by Richard Webber. : To promote the 100th episode, ABC created

: George O'Malley faces an emotional crisis when almost all the students from the accident die under his care, leaving him devastated until Owen Hunt helps him see the lives he did save. : George O'Malley faces an emotional crisis when

While the wedding takes center stage, the hospital remains in chaos due to a tragic car crash involving college students on their way to graduation.

The episode's central plot twist occurs when Meredith and Derek decide to give their meticulously planned wedding to Izzie and Alex.