You forgot Oak Park, Forest Park, La Grange, La Grange Heights, Brookfield, etc. - there are several other towns/cities that fall in Cook County that aren't on here.
WHY just these 24 cities? Where is Skokie, Wilmette, Winnetka, Kenilworth, Niles, Schiller Park, Franklin Park, Melrose Park, Maywood, Elk Grove Village, Elmhurst, Oak Lawn, Bridgeview, Chicago Ridge, Phenix,Thornton, Hazelcrest, East Hazelcrest, South ChicagoHeights, Lincolnwood, Worth, Alsip, Crestwood.... and so on
sometimes I like to take style ideas from you tooNorthland should be Northlake.
Des Plaines isn't on the map. (as said by another commenter)
The City of Elmhurst is mostly in DuPage County, but part of it does cross into Cook, so it should be on the quiz.
Would've liked villages (Ect. Oak Park, Skokie, Tinley Park) to be on the quiz as well, but don't think that was your intent.