I would say that alienation is also a critical connection between Pablo and Pink.  Both characters perceive reality quite differently when they are alienated from it.  This divided state of consciousness is one of the reasons why the perception of reality is so stark in both:  They are divorced from it.  There is a certain level of seeking to be detached from human consciousness, in being "comfortably numb."  Pink becomes farther and farther removed from reality and Pablo becomes absent from it when he learns of his own death.  Both of the figures seem to be alienated in such a manner that traditional modes of emotional expression are not as present as one would think it it to be .  Both realize that within this divided consciousness, freedom is a challenging element and that consciousness is something where the divided experience is a part and something that which navigation is essential.

Tough question.  I'm guessing one comparison could be how both of the main characters, Pink and Ibbieta, both had to face a tyrannical, overpowering force: Pink faced a judge, who blurts out how Pink deserves the "full penalty of law"; Ibbieta, on the other hand, also faces interrogation from an oppressive military force who wants him to reveal an acquaintance's whereabouts or face death by a firing squad.

We know that Sartre was an existentialist, which is clearly seen in many lines in the short story; similarly, Pink seems to struggle to find some sort of meaning to his life as well: he seems to simply give up at times just like Ibbieta does.

I may be stretching here, but both main characters also seem to harbor quite a bit of hostility: Ibbieta narrates his thoughts about how he hates the others and finds pleasure in teasing the guards.  Pink seems quite complacent, but can quickly fly off the deep end or do something extreme like join a Nazi-like extremist group.