Thanks for the response guys.
A little more about the scene. None of the snakes or reptiles in the pit on display at the time of the shoot were dangerous (well at least not life threatening). In the bags on the ground were the dangerous buggers.
Theses guys did come out not too long after I shot this panorama and when they did were kept in the very centre of the pit and were handled by only one of the guys from National Parks & Wildlife while he instructed and gave information via a wired headset. He went on the say that in reality these snakes are not aggressive attackers and the only time they are known to bite humans is when they are tormented or accidentally trod upon etc.
Also of note is that these snakes are milked before a public presentation to reduce the likelihood of a life threatening bite and that the venom is used as part of the anti-venom program.
As for shooting the panorama, it was not my intention to get a staged shot. I was just wandering around shooting scenes as I spotted them. I'm sure a stage shot would be very good and maybe someday I will set one up. (when one of the presenters looked at me funny I did think about asking him to hold the snake up to the lens) But at the same time I had a million things going through my mind, family in tow and just wanted to capture a scene with a lot of people in it as these are far more challenging shots and capture real life. People move a lot and even the 3 presenters in the pit where walking around in circles.
As I was not using a panorama head as such I had to just have a guess at where I thought 90 degrees was and deal with the Roll, Yaw and Pitch issues in processing.
Amazingly Panoweaver 5 did a very good job stitching the images. The issue though was Panoweaver doesn't support alpha channels and masks. So I did a quick stitch with Panoweaver and looked at all the things I would have to deal with and then get on with correcting them.