When JB Fletcher first called Maude Winslow, she mentioned that she hoped she wasn't interrupting her dinner, since Chicago was two hours behind. JB Fletcher was in Boston at the time (Eastern time), which is only an hour ahead of Chicago (Central time). To be two hours ahead of Chicago, JB Fletcher would have to be 1000 miles into the Atlantic Ocean.
The Tricolour (Irish Flag) in the bar is hanging the wrong way round.
When Cookie the bartender shows Jessica the newspaper about Harry, the headline has the word Homicide misspelled as "homocide".