In the movie, at one point of the interview that provides the framing story for the Neo Seoul episode, Sonmi 451 tells the archivist about the night when Yoona 939 woke her. That night, Sonmi 451 would wake up to see Yoona 939 have sex with (possibly being raped by) seer Rhee. Sonmi 451 only tells the archivist she was woken by Yoona 939, and Yoona 939 was woken by seer Rhee.
Then, the following exchange takes place (transcript):
Archivist: Why would a Seer wake a server?
Sonmi 451: Perhaps you should ask him, Archivist.
At the time we see this excerpt of the interview, this sounds like a valid idea.
However, later on, we learn that some time before the interview, seer Rhee died from a soap overdose. Thus, it becomes clear in hindsight that asking the seer was not an option.
While it was a bit of a rhetorical question and she might have told the archivist in more detail, had he insisted, why would she make such an evidently unfeasible suggestion? Is there any background to this (maybe a remark found only in the novel that interrogating a dead man is actually an option in that universe), or was it just a writing mistake in the intention of making Sonmi 451 appear as a decent character who does not delve into the dirty details of what others did wrong?