When the calendar is changing to show the amount of time Ren's been gone, it goes from December 2014 to January 2014 at the end, rather than January 2015.
When it shows the calendar after Stimpy asks when Ren is coming home, the calender shows the year as 1994. After December, the calender continues into January, but the year still says 1994. It should say 1995.