A fellow comes home and finds the Mezuza scroll slipped out of the case and fell on the floor. Does this require any special sort of Teshuva? Is there any difference if it fell directly on the floor or if it fell inside the case?
Kitzur Shulchan Aruch Yalkut Yosef (Orach Chayim 690:5) quotes from the Shut Lev Hayim (of R. Hayim Phalakhi) that one does not fast after a mezuzah has fallen on the floor, because it has a lower level of holiness than tefillin, and as R. Yosef points out there, even the custom to fast when tefillin or Sifrei Torah fall is not sourced in Shas.
My understanding is that this refers to the mezuza even when it is outside of its case, because the reasoning 'because it's less holy' is applicable to the actual written parchment (Shulchan Aruch Y.D. 290:1).