The song "You are My Sunshine" was not originally going to be in the episode. The baby playing baby William was fussy so the producer asked his mom about a way to calm him. She said that she sang that and so he asked the woman who played William's mom to sing it to him and it worked. The song would later be sung by others most notably Kate sang it to Jack when he was born.
First story not to feature Mandy Moore as Rebecca
In the motel that Randall and William stay at, Randall makes the bed. When William questions this, Randall replies with "Well I guess thats one less thing for someone else to do." But in reality, the sheets in any motel would have to be stripped and washed after each guest, so his task is pointless.