Although I can't absolutely verify that this came out of an Brooklyn Dodgers scorecard, I nevertheless found it fascinating. Featured above is said to be a circa 1942 pamphlet that was originally inserted into scorecards for patrons at Ebbets Field in Brooklyn, as seen in an eBay listing.
It reads:
Mayor La Guardia has provided a system of safety for patrons attending ball games.
This park is not bombproof but as safe as elsewhere.
If opposite you seat you find the label
You will be expected to do just that during an air raid.