During Coburn's time in the WHL, he also competed in two World Junior Championships for Canada, winning silver in 2004 and gold in 2005. He later played an unfortunate role in the outcome of the 2004 tournament — with the gold medal game between Canada and the United States tied at 3–3 with less than five minutes left to play in regulation, Canadian goaltender Marc-André Fleury tried to clear the puck to avert a breakaway by the USA's Patrick O'Sullivan. However, Fleury's clearing attempt went off Coburn and into his own net, giving the Americans a 4–3 advantage that eventually won them both the game and the gold medal.