Unsubstantiated Assertions and other LiesHoward Dean's abortion myth - The Washington Times: Editorials/OP-ED - June 09, 2005
There must be a name for this kind of rhetorical device, where you toss out a tangential lie while talking about something else.
I heard Biden do do it recently on the radio. Hannity asked him some question, but before Biden answered if he threw out the False meme that Republicans were trying to undo 217 years of constitutional status quo regarding judicial filibustering -- completely twisting the truth upsidedown and backwards. And Hannity let it slide because he wanted to bite on the question he had asked.
It happens across days, too. I've seen a small lie deposited in a story or quote, and if enough people don't scream within a few days, then it's taken as gospel truth and used as a tool to bludgeon opponents. Can't think of other examples offhand tho.