Rashi on Exodus
אם עבד או אמה IF [AN OX SHALL THRUST] A MANSERVANT OR A MAIDSERVANT — Canaanitish servants (Mekhilta d'Rabbi Yishmael 21:32:1).
Sforno on Exodus
כסף שלושים שקלים, equivalent to the monetary value set by the Torah on a woman in her prime (between 20-60) The comparison reflects the part of Torah legislation that must be observed both by Jewish women and gentile male slaves.
Rashbam on Exodus
אם עבד, a gentile slave יגח השור, the one whose owner had been warned concerning the danger this animal represented (מועד). If the ox did not have any strikes against it but was a תם, its owner is not liable for damages.