Shemuel called Rav by his real name, "Abba": Eruvin 78a, 94a; Pesachim 119b; Taanit 4b
Rav was called to the Torah for the first reading, which normally goes to a Kohen, even if Shemuel was present: Megillah 22a
Rav always had Shemuel enter before him, to show respect to Shemuel: Megillah 22a
Shemuel ruling like Rav against Shemuel, in all but 3 cases: Menachot 41b
Set of joint statements with Shemuel on blood-letting practices: Shabbat 129a-b
Shemuel challenging Rav's students on something that Rav had taught them: Kiddushin 25b
Shemuel tore 13 garments when Rav's death was mentioned, saying, "The man I was afraid of is gone.": Moed Katan 24a
Angered by the pain Shemuel caused him in loosening his bowels, he successfully cursed Shemuel to be son-less: Shabbat 108a
Rav cited a law, and said he did not know the reason; "it is a Gemara [tradition]." Shemuel responded, "Abba does not know the reason? This is the reason...": Eruvin 78a
Rav Chiyya bar Yosef asked Shemuel regarding a certain debate, "Does the law follow you, or does it follow Rav?" Shemuel responded that the law follows Rav: Eruvin 90b
Shemuel and Rav lived by a yard around which all of the residents had merged, to permit transport in the yard on Shabbat. The wall separating their yard from another yard collapsed on Shabbat. Shemuel held there was no need to fix it, but he did so for the sake of privacy. Rav held one couldn't carry the item needed to fix the wall, and he turned his back on the proceedings, but he didn't protest as it was Shemuel's place: Eruvin 94a
