If you mean The Mile High Club (The zeppelin), it's hard to miss, so it's not an easter egg. The Lost one is kinda cool, but I never got into the show.
I bet there are quite a few interesting eggs around though. Needle in a haystack.
No, im talking about the hot air balloon
All Easter Eggs so far
Bubble Gun
Go to X:4249, Y:25990 coordinates to find a Bubble Gun.
Hot air balloon
Go to X:7392, Y:16151 coordinates. You can ride the balloon by shooting off the sandbags.
I Am Legend reference
Go to X:18207, Y:21543 coordinates to find a chair and desk at the end of a pier, similar to the scene in I Am Legend.