The Obamas actually ate lunch on their first date beside the fountain at the Art Institute of Chicago and not in a park as depicted in the movie.
When Barack and Michelle talk beside Lake Michigan the modern Chicago skyline is clearly visible in the background. Most notably visible in several shots are Trump Tower (completed in 2009) and the newer portions of the Lakeshore East development, neither of which existed in 1989.
Near the beginning of the film, a CTA Green Line train is seen on the elevated tracks. The train clearly consists of the newer 5000-series cars, which did not exist until 2011 and did not enter service on the Green Line until 2012. The film is supposedly set in 1989 when the 2000-series cars (four generations earlier than the 5000-series) would still be exclusively in use on this line.
Furthermore, although the "Green Line" markings are clearly visible on each car, the CTA did not assign color to each line until 1995, so this line would have been known as the Englewood/Jackson Park branch in 1989, not the Green Line as depicted in the film.
Furthermore, although the "Green Line" markings are clearly visible on each car, the CTA did not assign color to each line until 1995, so this line would have been known as the Englewood/Jackson Park branch in 1989, not the Green Line as depicted in the film.
When Barack convinces Michelle to go to the "Afrocentric" art exhibit "a few blocks away," they are not walking distance from the location, the Chicago Cultural Center.