Robin's wedding march song is the Robin Sparkles song "Sandcastles In the Sand"
Final episode narrated by Bob Saget as Future Ted.
At the beginning of the episode when Ted and Robin are talking and Ted mentions not wanting to hang out with the guy whose wives keep ending up dead at the bottom of his staircase, he is referencing the 2004 documentary series The Staircase (2004) which would later be added to Netflix and garner world-wide attention.
When Robin walks down the aisle, the organ plays 'Sandcastles in the Sand' which is the song that first brings Barney and Robin together, originally sung by Robin.
The song playing during the wedding is Pearl Jam - Future Days.