"So round, so firm, so fully packed" was the advertising slogan of Lucky Strike Cigarettes.
First appearance of Foghorn Leghorn.
First appearance of the Barnyard Dog (whose unspoken real name, according to the model sheets, is George P. Dog).
Foghorn Leghorn was closely based on Senator Claghorn, a character on 'The Fred Allen Show', whose trademark lines included, "Somebody, Ah say, somebody knocked," "That's a joke, son," and "Pay attention, boy!".
Foghorn's line "Open the window, Richard!" is a reference to saxophonist Jack McVea's 1947 hit song, "Open the Door, Richard." In High Diving Hare, when Yosemite Sam bangs on a closed door demanding that Bugs Bunny open it, he speaks to the audience, saying "Didya notice, I didn't say Richard?"