In the opening credits, a snake (a Mexican black kingsnake) slithers across a marble table (in a homage/parody to I, Claudius (1976), a historical/political drama series which starred Patsy Byrne). However, the snake doesn't go the way it should, and at the end is removed and replaced with an object (the object varies depending on the episode).
At the end of episode 2 ("Head") the year of production is given as MCXIIIV A.D. (which is not a valid roman number) instead of MCMLXXXV A.D.
The closing credits is set in a manor garden, where a bard (played by Tony Aitken, voiced by Jeremy Jackman) sings a ballad mocking Blackadder's exploits within the episode and Blackadder endeavors to apprehend the bard (with mixed results, depending on the episode).
The series title has a snake in the "B" of "Black-Adder".