Ratings: 25.0 million viewers

Guest star Kali Rocha (Sydney Heron) previously appeared in "Break on Through" and "Where the Boys Are".

A majority of the ferry boat accident scenes were not filmed in Seattle. Producers and writers visited the real Coleman Dock, where the accident was said to have happened, and used pictures of the area to replicate the scene while filming in the Los Angeles area.

During the episode, Addison mentions dyeing her red hair blond. In real life, Kate Walsh is naturally blond and often dyes her hair red for roles, including her role as Addison on Grey's Anatomy.

Meredith: (voiceover) Disappearances happen in science. Disease can suddenly fade away, tumors go missing, we open someone up to discover the cancer is gone. It's unexplained, it's rare, but it happens. We call it misdiagnosis, say we never saw it in the first place; any explanation but the truth that life is full of vanishing acts. If something that we didn't know we had disappears, do we miss it?

Alex: Where we going?
Bailey: We’ll know when we get there.
Izzie: What kind of situation? Fire? Flood? Volcano? 'Cause I’m not really dressed for a volcano.
Bailey: Stevens!
Izzie: Sorry, that was inappropriate. Sorry.

Richard: What's the news?
Mark: Shepard and Grey are on the rocks, Burke and Yang got engaged. You need highlights in your hair. That's why it looks so odd. (awkward pause) I'm gonna go save lives.

Meredith: I'm a surgeon. I do the rescuing. You are not my knight in shining whatever.
Derek: So we're gonna fight because I pulled you out of the tub.
Meredith: You have a place. You could sleep at it. And then you don't have to pull me out of the bathtub. You're everywhere, all the time, saying things.
Derek: This is the happy ever after part. And in the happily ever after, the guy is there all the time, saying things and the girls love it!
Meredith: Go to work, I'll see you there.
Derek: And just for the record? I am your knight in shining whatever.

Meredith: I did not try to drown myself in the bathtub.
Izzie: Hey, I ate everything out of the fridge last night. Everything. Including a tub of butter. There's no judgment here.

(in the elevator)
Preston: What happened to your hair?
Addison: (quietly) Leave him be.
Mark: He dyed it.
(pause)
Derek: But why?
(Addison whacks him with her newspaper)
Derek: Ow!
Addison: Leave him be!
Derek: What are you doing?!
Preston: Okay, but why?
Richard: Men who have gray hair are noticed less than men who... don't.
Derek: By who?
(Addison clears her throat)
Richard: Well ...
Preston: By the ladies?
(Mark starts laughing but turns it into a cough when Addison glares at him)
Derek: Looks good Chief.
Preston: Very natural.
Mark: Ladies'll love it.
(Addison grabs Mark, Preston and Derek and pulls them to the back of the elevator)
Addison: This man is alone! All alone! Do any of you even know what that's like? (to Burke) Lives with Cristina, (to Derek) dating the perfect twelve year old, (to Mark) Manwhore! His wife left him! After twenty-five years of marriage! So if the man wants to dye his hair for the ladies, let him dye his hair for the ladies! (Derek mouths "alright") Now leave him be.

Derek: It just doesn't make sense. Ferry boats don't get in accidents. They're safe, they're reliable. The moment you take one for granted along comes a container ship and boom. I have a thing for ferry boats.

Episode Title: Walk On Water

"Walk On Water" is the title of a song recorded by several artists including Aerosmith, Ozzy Osbourne, and Eddie Money.