I was wondsering the same thing as William. I feel it should have been pudimos, simple preterite.

Since no one ever answered this, I will toss out my thought, and maybe it will spark a discussion: my understanding of the preterite with poder is that it is indicative of being successful at being able to do something--" pude reparar la bicicleta"--whereas the imperfect indicates a general sense of being able to do something--we could see all of Barcelona, as could anyone else who went up there.

Can anyone corroborate or refute this?