I think I see what you are referring to in the Navigators, but I think it is just more of a case of being somewhat unclear in the way things are ordered.
On the first page of the Navigator for Day 3 (Monday, January 21, 2002), there is an ad for the 70's disco night that says:
<div align="Center"><font face="Helvetica, Arial,sans-serif"><b><i><big><big><big>70's</big></big><br>Disco Night</big></i></b><br>Join your <i>"Groove Staff"</i> for a night of<br> dancing with special appearances by:<br> <i><b>Gloria Gaynor, John Travolta<br> & The Village People</i><br> <br>11:00pm<br>Rockin' Bar D<br> Deck 3, Forward</b><br> Try our 70's "Stayin' Alive" Cocktail!<br> <i>(Guests 18 & older)</font></i><br> </div>
Even though it looks like the "18 & Older" comment applies to the cocktail, it really applies to the 70's Disco Night. The drinking age on board is 21.