UA 3914 then AC 594 at Houston
Chicago → Houston → Toronto
Timetable, Houston time
23:27UA 3914 from Chicago at the gate
15:30AC 594 to Toronto leaves the gate
16 h 03 apart on the timetable, overnight
AC 594 leaves 16 h 03 after UA 3914 arrives on the timetable: more than half a day, so not a connection we count.