Here's a stitched panorama showing the SWC in the deployed location (A14-66-9302 to 9309).
In the film, only the portion sticking above the distant horizon is actually visible, as the lower part is hidden by the bright lunar surface. It makes quite a convincing illusion of being distant even though it is only a few metres beyond the LM shadow.
Mystery solved
(If you're wondering how the SWC can appear in the background of Mitchell coming down the ladder during the first EVA, when it was Mitchell who deployed it on the surface, it's because Mitchell went back inside to change the comms switch after deploying the high-gain antenna (and SWC). The film shows him coming out for the second time.)
Distances can be deceiving when viewing objects on the moon as the SWC was not far from the LM