The report says Canada's defense department was notified, but that with the help of United dispatch staff the flight crew confirmed it to be a communication issue and not a hijacking.
The report on Transport Canada's website said the U.S. Federal Aviation Administration reported that United's corporate office had indicated the pilot "had inadvertently squawked a 7500 code after spilling coffee on the aircraft's radio equipment, which interfered with the communications equipment."
"The flight crew had advised that they had communication problems and subsequently reported that they had some navigation problems as well, and from there the pilot in the command diverted the flight onto to Toronto," Maryse Durette, a Transport Canada spokeswoman, said Wednesday.
United spokesman Rahsaan Johnson had said Tuesday that the pilot elected to divert the flight rather than cross the Atlantic Ocean while experiencing a communications problem. United did not immediately return a call Wednesday to comment on the reported coffee mishap.
The Boeing 777 was carrying 241 passengers and 14 crew members. Johnson said United flew them back to Chicago on another plane and put them up in hotel rooms overnight.