I could easily echo many of the same things others have mentioned!
- In relation to foods, one of the little things I like is how you have to catch the peanut in SotN!
- In the 64 games, I like that they included the statue of Mary crying teardrops of blood...that then becomes an enemy!
- The brief reference to the CV bat, that is eaten by Balore in AoS
- Many of the background details mentioned, such as the corpses on pikes, rats in the ceiling in SotN, and prisoners rattling their cell bars.
- The storm blowing the curtains and rattling the windows (I'm pretty sure in the start of SotN, and maybe in another game too?)
- "Puzzle" type sequences, such as:
- - a few in HoD where you beat the giant knights backwards into stuff
- - the gears that open the secret room in the SotN clock tower
- - the hammer game in either AoS or DoS (where you have to ring the bell!)
- - the platform you ride in AoS, where you have to press the d-pad to get through
- - getting the Pneuma glyph in OoE
And though it maybe isn't a "little detail", but I really like learning of new secrets and shortcuts, like the secret elevator in the outer wall of SotN (you can access the same room later after you get the mist form). However, that's the only secret/shortcut thing I can remember at the moment.