This video shows President George Bush welcoming Queen Elizabeth II on her White House visit in 2007.
The President says, “You helped our nation celebrate its Bicentennial in 17—”
Realizing his mistake, Bush corrects himself and continues, “—in 1976.” What you can't see is Queen Elizabeth glancing over at him and muttering something. To his credit, Bush accepts the moment in good humor, adding, “She gave me a look that only a mother could give a child.”
Annoying the Queen is a bipartisan endeavor. When Jimmy Carter was president, he kissed the queen on the lips! She was properly outraged. Sadly, there's no good video of that moment, though.