OK, can anyone enlighten me. I'm sure there's a rational explanation. Other than time travel, or writers got flimsy with timelines that is... wait! They did it again?!

Jimmy Napolitano: I'll kill your brothers, your uncles, your father, and then after their funerals I'll kill you.
Gibbs: No brothers. No uncles. My father passed away 16 years ago. But I do have 3 ex-wives whose names and addresses I will gladly fax on to you. [we hear the sound of Jimmy hanging up] Huh! He hung up!
-- The boneyard [2.05]

Ziva & McGee: Gibbs has a father!!!
Tony & Abby: Tell me everything!!!
-- Heartland [6.04]