The son of the man Robin is dating is the same kid that taunted Marshall about the Super Bowl score in Monday Night Football (2007)
When Doug walks in on Robin having breakfast, Robin calls Lily and says, "It's here, Lily. It's looking at me." Not only is this a quote from the famous 'Slimer' scene in Ghostbusters, but that Robin says this is a call back to the Pilot where, on reflecting on Ted and Robin's first date, Marshall mentions that one of the perfect traits Ted looks for in a woman is to quote from Ghostbusters. The quote is also repeated by Ted himself when he comes face to face with the goat in his apartment.