On Friday the 13th of May 22, David Tennant filmed his portion of the regeneration from the thirteenth to the fourteenth Doctor, according to Doctor Who Magazine 584.
The TARDIS was on set in front of a floor-to-ceiling green screen, similar to how it was set up for the first part of the scene filmed by director Jamie Magnus Stone with Jodie Whittaker as the thirteenth Doctor.
This time tenth Doctor actor David Tennant stepped out onto the set to film his portion of the regeneration as the fourteenth Doctor with director Rachel Talalay.
Talalay showed the first half of the regeneration to David Tennant on her laptop. After the thirteenth Doctor is encapsulated in regenerative energy on Durdle Door, the screen cut to black with the on-screen caption: “Over to you, Russell!”
According to the DWM article, some of the footage is reversed to pull back in on Jodie Whittaker so that the regeneration can happen close up on the thirteenth and fourteenth Doctor’s bodies.
The shot of David Tennant with his arms flung open is lined up with the previous footage of Jodie Whittaker on the camera monitor.
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Tennant took a selfie with the TARDIS on set. “I’ve got to send Jodie this,” he told DWM, gleefully. “I’m texting her and sending her pictures, because obviously she isn’t here, but she’s my mate, and we’ve got her on a screen to line me up…”
A stand-in was also employed to help facilitate the filming.
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Adam Green edited the last few minutes of footage for the special together with with the previous regeneration footage. Green completed the work of editor Rebecca Trotman, who successfully suggested rearranging the order of the thirteenth Doctor’s last lines. The computer-generated effects for the regeneration were created by Ben Pickles.
Doctor Who returns November 2023 with three specials celebrating the 60th anniversary of the program.
Doctor Who Magazine 584 is available at newsstands in the UK and by digital issue on Thursday, November 10, 2022.