Bill and the Doctor hit up London’s last Frost Fair in 1814 during the third episode of Doctor Who Season 10, titled “Thin Ice” — but it’s not the first time that the Doctor has been to that exact fair, because he once took River Song ice skating there on her birthday.

In “Thin Ice,” Bill and the Doctor go sightseeing at the Frost Fair only to get wrapped up in the mystery of a monster snatching people from beneath the frozen River Thames. The last and greatest Frost Fair historically only lasted four days in 1814, and it was famous for including an elephant walking across the frozen ice below Blackfriars Bridge. An elephant can be seen in one of the trailers for the episode.

After a brief stint in period garb — including a delightful top hat worn by the Doctor — Bill and the Doctor venture below the ice in diver’s suits to find the beast.

And so, considering that the fair only lasted four days, it would be almost odd for Bill and the 12th Doctor to not cross the paths of River Song, the Doctor, and Stevie Wonder — that is, if what River told Rory in the 2011 episode “A Good Man Goes to War” was true:

River: It’s my birthday. The Doctor took me ice skating on the River Thames in 1814, the last of the great Frost Fairs. He got Stevie Wonder to sing for me under London Bridge.

Rory: Stevie Wonder sang in 1814?

River: Yes, he did, but you must never tell him.

See for yourself, complete with River in period garb.

Whether or not this little continuity mix-up will be addressed in “Thin Ice” remains to be seen, but it’s doubtful we’ll see Alex Kingston reprise her role as the Doctor’s wife anytime soon, if at all.

“Thin Ice” airs Saturday, April 29 at 9 p.m. Eastern on BBC and BBC America.

Photos via BBC America