Aspect ratio on Blu-ray

Just saw the Blu-ray for this. Most of the movie is framed to 1.75:1 and feels just a touch cramped, making for an occasional awkward framing. It really, really feels like it was shot for 1.66:1. And then, sure enough, two scenes (near the end --- one from the fight, and one of the last sequences in the corridor) are framed to 1.66:1. What's the deal? It's Criterion, so I'm sure they would've respected the director or DP's original intentions, but why does it jump around?