I have the scary terry skull and plan on using him next year as my helmsman.The head was a Scary Terry skull which I attached to a $12 plastic skeleton.
The cannon was made from black PVC pipe plus a frame made from scrap 2x4. I hid a fog generator under the cannon barrel and piped it through the barrel.
The audio was done in two parts - Dead men tell no tales and Crossfire by Nox Arcana. I ran them through Audacity (audio adjuster) to bring out the vocals and put them only on the right channel (which fed the Scary Terrry skull).
The left half had the cannon salutes from Crossfire (again, suppressing the background music). This was recorded on the left channel which fed to the low filter side of a 3-channel colour organ to drive the red light in the end of the cannon.
Does that give you enough info?