Owen says Megan has been missing and presumed dead for TEN years. This confirms the time line of Seasons 1, 2 and 3 being Year One in Meredith's story. Seasons 4 and 5 being year Two and each season after being one with the exception of Season 11 being years Eight AND Nine. Owen joined the hospital in year Two.
Megan Hunt suggests that Owen bring out his kilt and bagpipes to entertain her. This is likely a nod to Kevin McKidd's Scottish origins, he's from Elgin in Scotland.