When Carol answers the phone from Doug on line two she picks up the phone and starts talking it shows that line 2 is still blinking
Doug Ross tells Carol Hathaway he was waiting for her at the corner of Dearborn and Clark. Dearborn St. and Clark St. run parallel to each other and do not cross, so this would be impossible.
When Anspaugh is having a discussion with Weaver about Synergix he calls her Carol.