It's interesting that the writing and characterization was well done enough that hentai elements are not even necessary.

However there are two scenes in the anime that make me think they were abbreviated from the game:

The second time Shiro (SPOILER)catches Saber in the bathtub and she's actually flustered and embaressed. As opposed to the first time where she's totally unselfconcious.

The scene where Rin (SPOILER)transfers some of Shiro's magic circuits into Saber. Of course it requires them to be in close physical contact. I could even imagine Rin saying in the game: "The only way to save Saber is to sleep with her!"