My google calendar is off by one hour for all my shows as well.
Google calendars use UTC time.
So for instance, the show "Once Upon a Time" airs in the US eastern time zone during standard time (say February 1st) at 8 PM EST, or UTC -5 which is 0100 UTC.
Today, during daylight savings time, 0100 UTC translates to 9 PM EDT, which is exactly where my Google calendar places it.
It seems to me that TVRage should be changing its iCal feed to take into consideration daylight saving time. Because, ABC is now broadcasting "Once Upon A Time" at 8 PM
EDT, which is 0000 UTC. If Google were to receive the 0000 UTC time, it would place the show properly on my calendar.
This is my theory, it could be complete hooey! I hope it made some sense because this time change drives me crazy!
BTW, I used this site (http://www.worldtimebuddy.com/) to help me with this stuff. You my have to add the "UTC / GMT" time zone