The actress who plays Sansa Stark had a Targaryen dragon by her name in the opening credits.
This wasn’t the only instance of a mistaken sigil either, as Iain Glen, Emilia Clarke, and Jack Gleeson also got the wrong animals at different points.
Now, this was well before viewers had reason to suspect that Rhaegar + Lyanna = Jon, and it was pretty clear that this had to be a mistake, but book readers familiar with all the theories about secret Targaryens undoubtedly got a laugh.