Much of Seasons 1 and 3 (especially the latter) are based off that from the manga the series is based off from. Season 2 has an entirely separate from the source material.
Sebastian never refers to Ciel by name and only refers to him as "My lord" or "Young master". This stays true throughout the entirety of season one and two, Book of Circus, Book of Murder, and Book of the Atlantic.
'Potentia Revere' is the Phantomhive motto, and is seen on the stone bench in the first opening, Ciel's ring, and several other places in the series.
J. Michael Tatum (Sebastian) also voices Kyoya in Ouran Highschool Host Club.
Brina Palencia, the actress who voices Ciel, also voices his mother, Rachel Phantomhive.