Gears
If you look closely at the set of Vidal's room, you'll notice a lot of large gears and beams in the background. Sure, maybe there's some logical explanation for why these would be in his room; maybe the machinery décor was the "in" thing back in 1940s Spain.
But what stands out are how these gears mirror the gears in Vidal's father's watch—you know, the watch that we see him fixing in the first scene of him in his room.
We know the gears in the watch are useless. The watch was smashed on a rock and broken, only able to tell the time of Vidal senior's death. But both sets of gears have a more symbolic significance.
They're a visual representation of Vidal's character. They speak of his need for rule and order and control. Vidal is a man of action, a military captain, who very literally forces his will upon the world just like the gears do in their cold, mechanical, unthinking way.
But, like the broken gears of the watch, Vidal's will is ultimately thwarted, and any meaning or memory he was trying to perpetuate was lost along with his life.