my hellcqnnon doestn have a wound...is this a print error?

I don't think it is. Mine doesn't have one and neither does the disk image on BGG.

right but it's strange that evry elite and war machine has an additional wound i dont really sede why hellcqnnon shouldnt

It is different from other war machines but so are many other aspects of the creature. The hellcannon has the most hit points of all units and against ranged fire especially is pretty durable. It is also the most maneuverable, with its printed one big disk flip and its extra move while attacking. This coupled with a big impact and the demonic trait makes it quite the unit. I can personally attest to how much fun it is to drop it in front of a archer line from a kairos summon and then next turn just impact them all to death. admittedly it had been empowered and deployed into the crags, but it was fun. I think I ate like three empire crossbowman with impacts and a pistoliers on the ranged attack.

right but it's strange that evry elite and war machine has an additional wound i dont really sede why hellcqnnon shouldn't

It is different from other war machines but so are many other aspects of the creature. The hellcannon has the most hit points of all units and against ranged fire especially is pretty durable. It is also the most maneuverable, with its printed one big disk flip and its extra move while attacking. This coupled with a big impact and the demonic trait makes it quite the unit. I can personally attest to how much fun it is to drop it in front of a archer line from a kairos summon and then next turn just impact them all to death. admittedly it had been empowered and deployed into the crags, but it was fun. I think I ate like three empire crossbowman with impacts and a pistoliers on the ranged attack.

right but it's strange that evry elite and war machine has an additional wound i dont really sede why hellcqnnon shouldn't

My guess would be that larger pool of toughness compensates for that wound. think of it in terms of hits. many ranged attacks deal 3 damage. The bolt thrower would die from two ranged attacks of three damage each. The five toughness hellcannon will also die from two ranged attacks of three damage. with that five toughness, the hellcannon ranged artillery that can take a units counterattack damage and still survive. and given that it wants to land on top of things that seems like a good thing. I understand what you are saying, that from a point of symmetry there is reasoning for it to have it, but I feel confident in saying that if you play some test cannons with a 5 toughness 2 wound hellcannon, you will find it much better then its 12 points deserve.