Gatwa, who plays the Fifteenth Doctor, and Sethu, who's character name is yet to be revealed, were seen filming in Penarth in Wales, which has been dressed to look a fair bit like Miami in the 1950s.
In one video, shared online by @set_dw, the pair could be seen hand-in-hand, running past The Palazzo (which had Rock Hudson's name up in lights).
Gatwa, who has already shown off his style on Doctor Who in the 2023 Christmas episode The Church on Ruby Road (we haven't recovered from the glorious kilt) can be seen rocking a blue suit, while Sethu appears to be glammed up in a yellow dress.
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Other shots from set show vintage cars, while more show the TARDIS looking a little out of place amid the US sights.
Season 15 of Doctor Who (Gatwa's second season) is currently filming, with it being reported that Sethu has taken over from Millie Gibson as the main companion.
Gibson, who is starring as Ruby Sunday alongside Gatwa in season 14, will instead be taking on a smaller role and has already been seen on set filming.
While details are currently thin on the ground about Gatwa's second season, we do know a vague release window.
Previously speaking to The Big Issue, showrunner Russell T Davies said: "If I sound a bit hyper, it's because I just this morning delivered a Doctor Who script that will be on air in May 2025.
"And it's brand new. It does things we've never done before. The writing really pushed me. It's such a mad episode, I had to deliver it with a diagram explaining what's going on! I’ve never had to do that in my entire life before."