December 31, 2010[nb 1] is the 31st day in the month of December 2010.
- 00:16 EST: Red Arrow is pursued by Aquaman, Flash, and Green Arrow in a Washington, D.C. subway. He manages to elude them.
- 07:16 EST: At the Cave, Batman reveals to the Team that Red Arrow was the mole, while Red Tornado reveals that Red Arrow is a clone.
- 23:16 EST:Black Canary, Red Tornado, and Red Arrow arrive at the Watchtower.
- ↑ Series producer Greg Weisman stated that even though the series does not have a "canon year", the production team based the days of the week on the 2010 calendar. (Weisman, Greg (2011-11-18). Question #13695. Ask Greg. Retrieved 2011-11-18.)