Motherboy was not a real band. If you look at the pictures they show during the episode, you'll see that it's really just the male members of the cast in costumes and makeup.
Gob and his wife would have known each other besides their marriage night as they lived together for about a week after the night.
Outside of Maggie's house, Michael tells George Michael "We're like a team. We're like Red McGibon & Bullet". This is a reference to the radio and movie serial that Uncle Jack (from the episode "Ready, Aim, Marry Me") starred in.
While they are sitting outside of Maggie's house, Michael makes a call to trace the number that was left on her door. When getting off of the phone, he says "Thank you, Mr. Parmesan". This means that Michael called the family's private detective Gene Parmesan, who appeared in the episode "Amigos".
Also, the "You're Killing Me, Buster" sign was seen in that episode.
In typical Hollywood fashion, Maeby's film of Ernest Hemingway's The Old Man and the Sea has been given the name The Young Man and the Beach.
Michael acts surprised when the gay cops uncover the bundle and find it's not a baby, but he must have known. He snatched the bundle away from Maggie in a way that would have hurt a real baby, plus there's no way the fat suit in the bundle had the weight and consistency of a real baby.
Maggie moves to have the fat case thrown out when Barry lifts up Loretta's shirt, but since she is representing the plaintiff, she should naturally not want the case thrown out, because then her client wouldn't get any money.
The two gay cops were previously seen on the episode "Not Without My Daughter", were they both brought their daughters (not seen on screen) to work. It is possible that they had daughters in other relationships, but it doesn't seem that they were written as gay cops back then.
When Buster is on the Army bench, he covers it up so that it says "Arm Off".
Barry's time at rest stops is first mentioned in "Let 'Em Eat Cake".
Since George Sr. started hiding in the model home's attic, many boxes have been visible labeled as containing the belongings of "Tracy," Michael's dead wife. However, in this episode, and continuing through the second season, some boxes now spell her name "Tracey," sometimes with both spellings shown in the same episode.
In the epilogue, the narrator says Tobias taped a day's worth of his own words "to see what Michael was referring to." However, the snippets on the tape were from previous episodes, and therefore before Michael made the suggestion. (Also, since when can tape recorders hold an entire day's worth of content?)
Moses Taylor (TV's Frank Wrench) has a gun organization called "Hands Off Our Guns", or H.O.O.G. This is a reference to the pilot episode, where Lindsay held a charity fundraiser for H.O.O.P. (Hands Off Our Penises).
During Tobias's scene at the bulletin board, a sad man looks at his bulletin of the Blue Man Group, and Tobias says they're literally blue. This is a callback to the season premiere "The One Where Michael Leaves" when he viewed the poster for "Blue Man Group" and thought it was a support group.
Sally Sitwell mentions feeling terrible for "whoever it was" whose car burned at the country club, yet later Stan Sitwell mentions his car just having been destroyed by fire. Sally was in the club parking lot, so wouldn't she have recognized her father's car, even burned?
In Buster's room, behind Michael, a map of Canada can be seen. This is a reference to the time Buster went to Canada for an operation.
Michael bought the car from the same man Gob bought "The Seaward" from.
In the Queen Mary, there is a well-placed "Park in Rear" sign. This has the same double-meaning as it did in "Afternoon Delight".
When Michael is talking to Lucille II in "Tobias is Queen Mary", the camera angle changes to focus on each character. In about half of the shots, Michael's collar is flipped up, while in the other half, it's flipped down.