I've seen that the model of the Retaliator needs a little fix in the model because the macro cannons that should be in the lower part are hidden.
Also it doesn't look completely symmetric as one side is slightly shown.

The battery of cannons is located under the ship, so can only see it if you pan underneath using Fleet viewer or in battle.
In the upper side the cannons are clearly seen.

But in the lower side they are hidden.
In the right side they are slightly shown.

In the left side they are hidden.

Inside the model you can clearly see that they are there in both sides.

I wouldn't call this a bug but I would like to see it fixed some day even if this isn't a priority.

Thanks for developing this great game,