Oh wow, thank you! For those who don't speak Spanish, here's exactly what was cut out:

English Dialogue:

DENNIS: You're fooling yourself. We're living in a dictatorship.
A self-perpetuating autocracy in which the working classes--
WOMAN: Oh there you go, bringing class into it again.
DENNIS: That's what it's all about if only people would--
ARTHUR: Please, please good people. I am in haste. Who lives
in that castle?
---CUT BEGINS HERE---
WOMAN: No one lives there.
ARTHUR: Then who is your lord?
WOMAN: We don't have a lord.
ARTHUR: What?
DENNIS: I told you. We're an anarcho-syndicalist commune. We take
it in turns to act as a sort of executive officer for the week.
ARTHUR: Yes.
---CUT ENDS HERE---
DENNIS: But all the decisions of that officer have to be ratified
at a special biweekly meeting.
ARTHUR: Yes, I see.
DENNIS: By a simple majority in the case of purely internal affairs,--
ARTHUR: Be quiet!
DENNIS: --but by a two-thirds majority in the case of more--
ARTHUR: Be quiet! I order you to be quiet!
WOMAN: Order, eh -- who does he think he is?
ARTHUR: I am your king!

So in Spanish, the dialogue goes like this (just including the the lines before and after the cut), which is very abrupt and makes Dennis' response into a non sequitur:

ARTHUR: Por favor, por favor! Tengo prisa, buena gente. ¿Quién vive en ese castillo?
DENNIS: Pero las decisiones de ese funcionario deben ser ratificadas en una asamblea quincenal, por una mayoría sencilla en caso de ser asuntos

Backing that up, I found another clip which explicitly mentions that it was censored and links to a newly dubbed version without the cut (seems the redubbing was done in 2008 for a DVD release).

I'm pretty surprised there's no mention on Spanish Wikipedia. If I were a native Spanish speaker and could track down a solid source I might add it myself. Some quick Google searches in Spanish didn't turn up anything useful, but I wonder if there are any books or other print sources which detail Francoist censorship of foreign media.

Also TIL that "fortnight" is quincena in Spanish, which is basically "fiftnight" (although -eno is a more general suffix).