Nicholas Colasanto died of a heart attack five days after this episode aired. He would still appear in two more episodes, shot shortly before his death.
Shelley Long was pregnant at the time so the script was written that Diane was the only one who was skinny enough to fit in the vent and then gets stuck under the floor after she crawls through the vent in order to hide Shelley Long's pregnancy.
Sam and Diane are imitating Señor Wences when Sam says, "S-All Right?" while he closes the grate door.