Looking at this big screencap carefully, particularly juxtaposed with 3PO on the forest moon's surface, we couldn't help noticing that it's night directly under the Death Star... but at the same time it's daylight where 3PO is, near the shield generator, under the Death Star.

There's an online analysis of the time sequencing of the events which notices the same thing, and resolves it by positing that Han, Leia, and Chewie are captured inside the shield generator (the previous strip of Darths & Droids) during the day, then the Rebel fleet arrives during the night, a bit before dawn (as seen here), and then the next scene where we see the Imperials march Han, Leia, and Chewie outside must take place the next day, after spending the whole night inside the shield generator building.

This interpretation is not supported by any other observation you can make from the film - and makes so little sense, especially given that Luke's encounter with the Emperor is shown intercut as though it's happening at the same time - that we prefer to just think of it as a continuity error in the film and move on.

Transcript

{Lando and Nien Nunb bring the Millennium Falcon out of hyperspace near Endor}
GM: Han's radio squawks again.
Lando: Lando here. We've arrived at the Peace Moon with the Rebel fleet.
C-3PO: That's a bit soon. We haven't got a ship yet.
Lando: What happened to the Imperial shuttle?
C-3PO: Han crashed it.
Lando: Well it's a bit late to call off our obvious attack now.
C-3PO: On the bright side, we still have the element of surprise.
C-3PO: For the next 30 seconds.