The flight was about to leave from Rygge airport near the Norwegian capital, Oslo, when it was evacuated.
Two men were detained by police after their behaviour aroused suspicion but were later released.
The situation was "back to normal", police said in a tweet. Ryanair said the passengers would also depart.
No suspicious devices were found on the plane.
News reports quoting a police official say one of the arrested men was British and the other was from Sri Lanka.
The reports said the men had been heard arguing loudly and the word "bomb" was overheard on the flight, which had been due to leave at 18:55 local time (15:55 GMT).
The evacuation in Norway came hours after Manchester's Old Trafford football stadium was cleared after a suspicious item was found.
It was later confirmed by British police that the item had been "accidentally" left by a private company after a training exercise.
A Ryanair flight from Norway to Manchester has been evacuated before take-off over a bomb scare which police say was due to a misunderstanding.