In the poker game, the corpse is holding Aces and Eights. This is known as the Dead-Man's Hand.
While it may be possible, it seems strange that Nash wouldn't have figured out he and Lisa were still married when he and Kelly married. Either way, with him still being married to Lisa, this means Kelly and he were never officially married as you cannot legally be married to two people at the same time.
The SIU move to a new location for the third and final time of the series. They are on a different type of boat now.
Yasmine Bleeth (Caitlin), was credited in the opening credits, along with all the other main cast members, however she was also credited as a Special Guest Star. It seems she initially was to have a recurring role, as in future episodes she is not credited in the opening credits, but as Special Guest Star only. It is possible the wrong opening credits were used for this episode, which reflect her addition to the main cast later in the season.
This episode takes place four months after the season three finale.