Visible crew/equipment: When Angier goes to Tesla's laboratory and walks to the gate, on the far right side of the fence a figure can be seen, apparently holding something ahead. It seems to be one of the film crew holding a boom mike upright. (00:09:59)
Visible crew/equipment: When Angier and Tesla have their first talk on the balcony, take a closer look at the moment where Alley pours the tea into Angier's cup, and you can see two stage lights and a boom microphone reflected on the teapot. (00:50:30)
Visible crew/equipment: In the final shot where Angier lies dead on the ground with the theatre on fire, the camera can be slightly seen reflected on the glass box with one of many Angier's doubles inside once it does a tracking shot. (02:04:52)
Answer: It's Bale, at least whenever you can see Fallon's face. The same way they do twins played by the same person in any other film.
Phixius ★