River is “The Queen of Mischief” in Series 7
Moffat suggested that her appearance this time will be more of a one-off adventure, as they already did the “big River Song story” last year.
“She’s so the queen of mischief in [Episode 5],” teased producer Caroline Skinner.
Io9 asked Moffat if there’s any place left for the character to go after seeing her “birth, marriage and death,” as he put it. “There’s also just having River turn up and have fun on an adventure, which is fun too. She’s one of the people who can draw the Doctor into a mad adventure very, very quickly and very, very easily.
“That’s a different way of doing it. Sometimes you’ll just see her phoning the Doctor up and saying, ‘Let’s go see that.’ There’s that part of the relationship too, which is big bonafide adventure.”
So perhaps some of those gaps in her timeline will be filled in eventually.
Quizzed on whether we’ll see more of River’s “night journeys” with the Doctor: “I don’t know if we’d be allowed to! Heaven knows, I think it’s important that characters keep secrets from their writers, and the Doctor has not given us the information about what happens on those nights. He’s a gentlemen. Gentlemen never tell.”