Police said they told people inside the northern Alberta airport to leave as a precaution while officers searched for the man.
Insp. Gibson Glavin said it turned out there was no threat. He said the man chose a poor topic to discuss in an airport.
"A lone male was arrested and is currently in custody for making comments in reference to a dangerous device," Wood Buffalo RCMP said in a news release.
"Threats made against the safety of an aircraft and /or its occupants are criminal code offences."
Fort McMurray Airport Authority said about 300 passengers on four flights were directly affected and others may experience travel delays.
"Staff worked hard to ensure that passengers were rescreened as efficiently as possible once returning to the terminal, and airline staff made themselves available to answer passenger inquiries," Joanne Barnes, spokeswoman for the airport authority, said in a news release.
"We are very grateful to the RCMP for their prompt, professional response to the situation."