Martin is interviewed for the position of Portwenn physician in episode 1x01 "Going Bodmin". Marin, Louisa, and PC Penhale search the Castle Hotel for Mrs. Tishell and missing James Henry in episode 5x08 "Ever After".
Source: Doc Martin Online
The Doc sees a VW that was left parked on the beach floating in the water after the tide rose in episode 1x01 "Going Bodmin".
Martin visits his aunt out at her farm in episode 1x01 "Going Bodmin".
Doc Martin takes over the clinic in the small town of Portwenn in episode 1x01 "Going Bodmin".
Source: Fern Cottage
Martin walks past the school and sees Louisa inside teaching while wearing an eyepatch in episode 1x01 "Going Bodmin".
John Slater's boat is mored in the harbour in episode 1x05 "Of All the Harbours in All the Towns".
Doc Martin picks up his parents from the train station in episode 2x06 "The Family Way".
From episode 3x04 "The Admirer".
Martin and Louisa go on their first date at a music performance in episode 3x05 "The Holly Bears a Prickle".
From episode 3x07 "Happily Ever After".
Louisa gives birth to their child in a pub in episode 4x08 "The Wrong Goodbye".
From episode 5x02 "Dry Your Tears".
Louisa, Martin, and Penhale track Mrs. Tishell and James Henry to a remote holiday home on the cliffs in episode 5x08 "Ever After".