When Rick Walker is in the bar with Sam, he recognizes Coach as a former pitching coach for the Boston Red Sox. Yet in future episodes of Cheers, Coach is always identified as a former third-base coach.
Diane's facial tick is never mentioned again.
Sam goes to pour Rick Walker a beer. Then it magically appears in front of Rick before Sam returns from the tap.
When Sam slides and curves the beer mug to Cliff around the bar corner, glints of reflected light can be seen in several places along the thin filament attached to the glass which makes this trick possible. These can also be seen again later when he repeats the trick with Dianne.