Known Bugs (Apocalypse)
Cityscape bugs
Firing Infatuated Agents
This happens if you have more than twenty combat agents (or biochemists, or engineers, or quantum physicists) assigned to single base. Only the first twenty specialists are visible in the hire/fire interface. The others cannot be fired from the agent interface.
Firing specialist (agent, biochemist, engineer or physicist) #1 fires agent #21 (and engineer #21 if present, and quantum physicist #21 if present) as well. Firing specialist #2 fires agent #22 (and engineer #22 if present, and quantum physicist #22 if present) as well.
And so on.
To fire >#20 specialists one needs to "transfer" some <#20 specialists to other base. Then it's still only possible to fire only first 20 specialists, but those which were further down the line are now visible. This can be done without unpausing - so it's possible to transfer those specialists back once proper guys/gals have been fired.
Rendor Plasma Shot Undercount
Per NKF's research ( http://www.xcomufo.com/forums/index.php?showtopic=242028127 ), the Rendor Plasma gun (an air vehicle weapon) actually has all 140 of the shots it used when loading up. The game divides this by two, reporting 70 shots.
Is that base yours ?
When aliens get to your base by spreading through the tubes, the game treats your base as if it was a building owned by the government. Hence, the alien activity will start growing on the government, if aliens are spotted you will have an alarm, and if you start a mission, you will combat in a standard warehouse or slum scenario, rather than in your base.
Battleship ex nihilo
One of the Infiltration fleets (#17 on the UFO Incursions page) consists of one Battleship that inserts aliens, one Escort Ship, and one Battleship that bombs a building. This is the only UFO fleet in the game that has the same UFO type performing two different missions, and as such it runs afoul of a bug in the spawn routine. See, when checking whether there are enough UFOs for a fleet, the game checks for the presence of each UFO group separately, and the two Battleships are in different groups. As such, the game checks for whether there is 1 Battleship, 1 Escort Ship and 1 Battleship, not whether there is 1 Escort Ship and 2 Battleships, and may erroneously spawn this fleet (with both Battleships) even if there is only one Battleship in the Alien Dimension.
Time Lapse
If too many vehicles are on the Cityscape at the same time, you cannot choose the "Ultra Fast" time control option. This usually happens on the biggest Mega-Prime map on Superhuman where, due to the way some roads are connected in a criss-cross pattern with eachother, sometimes vehicles get stuck moving in circles eternally or if in one of those criss-cross sections of the map one exit was destroyed during UFO fights the vehicles will be unable to pathfind another way out, as they seem to try and always go for the shortest path, even if that one is destroyed, and will never try to go for an alternate longer path, regardless if one is available or not. To solve this issue, you have to use an X-Com Craft to either directly destroy some of the vehicles or use the Manual Craft Control (M to activate, LMB to shoot) to destroy the road/bridge the vehicles are on (no reputation loss).
Storage alchemy
When you sell off all of an alien artifact and it disappears from the sell screen, the game doesn't always re-point your stores correctly. One known possibility is all your Elerium-115 (potentially several hundred) being transmuted into GLM Air Defenses when Cloaking Fields are sold off.
Tactical section bugs
Poor pathway finding
The pathway finding algorithm will choose very poor paths when you move your men in the turn based version of the game. The path chosen will be OK only if you your men can reach their destination following a straight path and there are no obstacles around. Otherwise it will pick very crazy routes. The behaviour of the algorithm is particularly crazy when you are using flying units and more complicate routes can be chosen. Also, the path that your men follows when you move appears to be different from the one selected to predict the TUs left after the move, so that this prediction is often incorrect.
Agents travelling in time
When you start a mission in turn based mode, the clock will advance by a few seconds after each turn. But after that you have completed the mission it will get back to the time before mission started. The odd part is that the ship carrying the agents is ready to take off.
No night missions!
Missions will always happen in the light, even if it is night and the mission takes place outside of any building.
Crazy transportation
If you hire new men and the road to access your base is broken, your men will pick a car but will not be able to reach the base and will keep turning around and around. But as soon as you set the "ultratime" on he will get to the base regardless the road was repaired or not.
Quarreling with Transtellar is dangerous!
If you happen to upset Transtellar your men will not be able to move using transtellar cars. If you hire some men they will try to get to your base through the tubes, but they often will not be able to get to your base and remain stuck in another building. At this point if you then succeed into getting a better relationship with Transtellar, your men will not immediately get to your base, and some of them might remain stuck into their positions even running the ultratime. One way to unlock the agents is to transfer them temporarily to another base, another is to order the agent to any nearby building and then send a vehicle to pick them up.
Visual glitches
There are some glitches when you move your men flying very high, especially if tall structures are around. You will see "shadows" to appear and move here and there, and, after movement is completed, they will not be cleared until you force a complete redraw of the screen.
Resistance bug
In the turn-based mode when you are flying with the marsec armour at high speed (running) the stamina is unaffected, so that you can run as long as you like and each move has a reduced TUs cost. But if you run out of stamina everything works as if you were walking: the TUs cost of your movements is increased.
Spying capabilities
In turn based mode if you spot one or more aliens and you end your turn, the first steps of the alien that moves first (among the ones that you have spotted) are always visible, regardless that the alien is outside of the visual range of any of your men.
Big aliens visibility bug
Big aliens (Megaspawn, psymorphs) might not be visible to your men if part of their body is hidden behind structures. Even if the alien is sitting in front of you and half of its body is in sight.
Items limit in tactical combat
There seems to be a limit of items in tactical combat (roughly 500). If one takes a full contingent - 36 agents - to a combat, if there's too much equipment in their inventory some agents may not spawn and/or aliens (Anthropods and Skeletoids) may spawn without equipment. This *may* be a good exploit for dangerless tactical missions, but it will *not* give any points/credits for equipment that is missing - since it's not present.
Android Resistances
By default, Androids are assigned the Human resistance values. Meaning, they will just as quickly fall unconscious to stun damage as Humans and Hybrids, causing Androids to take 100% Stun Gas and 100% Stun (Stun Grapple, Psionics) damage instead of 0% Stun Gas and 20% Stun damage. This can be manually fixed by using modding programs such as "Apoc'd", which can be found here: http://www.strategycore.co.uk/files/apocd/, and assigning Androids to the Android Damage Modifier.
Design flaws
Cannot choose men in base defense missions
When an enemy corporation attacks one of your bases you will be immediately engaged into a base defense mission. The tactical screen limits to 35 the number of people that you can use in a mission. If there are more than 35 people in the base, only 35 will be active in the mission and you are not given any choice which man to use. You might find yourself fighting with injured agents or with poor agents that you were training. Additionally in these missions you have no option to get any weapons from the stores in the base. If you leave an agent bare handed in the base, you will fight with a bare handed agent!
Cannot rotate the view
Shorter aliens (Brainsuckers, eggs, multiworms, hyperworms) might be covered by taller structures, making them hard to see or tell apart. Being able to rotate the view would fix this.