A lot of buggy behaviors right now are probably just the results of the lag. There are several things you can do to minimize your lag and make the game ultimately more enjoyable. Lag is going to occur on either your client or the server, with different factors involved for each case. This mostly occurs on Abassa.
If your machine/graphics card aren't powerful enough, your client may lag out. Go into the options panel and choose a lower resolution to play at and/or reduce the graphics quality. I'm not sure if there is a way to have the game report on the current FPS, but most modern video card drivers have a way of monitoring your FPS. Of course, there's the usual regimen of closing down all other applications. For the rich, you can always buy more RAM or upgrade your machine!
If your server is lagging there's only one thing you can try, and that's to switch to a server with fewer pirates on it! This process is described here on the Maps page.
Sometimes when talking to an NPC, you'll choose an option, but nothing comes up. You can't walk away from them, because you're stuck talking to them. If this happens, you can press ESC to release from them. However, sometimes pressing ESC will shutdown the entire game, but I can't find other way to disengage from them. Pressing ENTER can also occasionally shutdown the client as well.
Weapon page disappearing
After awhile all pirates seem to get a bug where their weapon screen disappears. This is the screen that's supposed to let you decide which weapon is activated when you press each function key. Once this happens, you just seem to be forever stuck with the same weapons. Short of deleting the pirate and starting over, I haven't found a way to work around this bug yet. Whenever starting a new pirate now, I immediately get the weapons I want and arrange them to my liking the very first thing. I avoid going inside buildings, talking to NPCs, sailing, etc. until this is accomplished, since once it's bugged there's no fixing it. You can still use F1-F4 to select your weapons, you just can't change them around or use any new weapons you later obtain.
Locking up on loading screens
Sometimes pirates get bugged where they can no longer go anywhere that requires a loading screen. The loading screen comes up and just sits there. Often you'll hear the same sounds repeat over and over. Sadly, once a pirate gets like this, the only option seems to be to delete the pirate. A few people have been able to not delete the pirate and the bug was fixed with the next update. However, setting sail and engaging in ship to ship Combat doesn't require any loading screens, so when this happens to one of my pirates, I just send them out to sea!
Enemy ships that won't sink
It's very frustrating but sometimes you'll get an enemy ship so low on health it's actually negative, but it still won't sink! The ship is bugged and no amount of further shooting at it seems to make a difference. The ship will eventually crash minutes later, but you don't seem to get any plunder or rep from it. Until they get this bug fixed, you may want to avoid fighting Level 6 or higher ships, since you will have spent so much time unloading your cannons into her, only to not get credit for it. This may not be an actual bug, as when the ship reaches negative health icons will show on the ship. Fire the grapple hook at the icons and you will link to the ship. Most likely you need to raid the ship in order to finish it off.
It is possible to "fly" by walking off of a large sized ship (you have to jump/walk near the edge until the character starts floating) while sailing. Once you leave the ship, you will not fall. You can't get down unless you go back to your own ship. In a related issue, I did have a ship that every time I tried to board it, I wouldn't land on the deck, but rather a few feet above and would be flying. The 'fix' was to just sell that ship off and buy a new one.
When you're sailing a ship, sometimes when moving the camera around, it starts spinning crazy out of control. When this happens, just move your mouse down until it leaves the window, then slowly move it back up into the window.
If you own more than one ship and you bring up your ships to deploy one, the display window will be all messed up. Simply click one of the arrows to cycle through your ships and it will clear itself up.
Sometimes, if you get on a ship just when it sinks, you will end up swimming where the ship is, and afterwards, you will flip upside down and your legs will stick out of the water, I have experienced this glitch on 6/14/09 as the date, and when the glitch occurred, I was thrown into jail with my head facing the back wall. Now, after this, you will be backwards while you run forwards, when you press the down button, you will look like you are walking forward, in the direction the PIRATE(not the player themselves) is looking. Even after teleporting, you will be stuck in this way, until you log out. Even though you are looking backwards, when fighting enemies, the pirate won't look at them, but their weapons still work on them (if you are facing a crab, your pirate will be looking at you, but when you attack, the crab seems to take damage).
Sometimes when lag occurs while you are in motion, the game will not realize you let go of the button and will still have your pirate running. This can be temporary, or stay this way until you log off. To fix this bug just do a Blade Storm.
This happens mainly Port Royal and Kingshead, where you attack an enemy with zero Health, but he doesn't die or attack you. You can't do anything to kill it, no matter what you try. This happens to Undead and Royal Navy (Cadet)s mainly.
Unknown Name Error
When the game can't match an item found in a store, or loot to a name inside the game's files, Error, no name appears as the item's name.
Occasionally, the game will randomly crash in display a variety of error codes. Most of the time you can log right back on without an issue.