I know it's an old thread, but I have to disagree on the "useless" thingy for this type of failgold. Getting gold due to building an "overflow missionary" can be very useful in setting the science slider 10% higher for 1 turn "for free", plus, considering that this not only applies to missionaries, but corporation executives as well, it goes without saying that it helps a lot getting between 100 to 500 gold from the "executive failgold" to fund the next corporation expansion, as the gold comes without any negative modification of the science slider, the executive gets built
despite the failgold (if it's just 1)
and the hammer overflow in the city that built the "failed executive" is unchanged (allowing to switch back to producing executives the same turn, assuming the said executive is consumed in expanding the corporation that turn).
So yes, to a point, you
are still able to get back the missionary / executive back in the queue, because if you build those units in multiple cities, the failgold happens before actually producing the last "legal" (according to the rules of the game) missionary / executive, because the game counts the missionaries / executives that
are being produced, not the ones that are already built (so if you produce the missionaries in 3 cities, or the executives in 5 cities, you can get the failgold even at the 2nd missionary / executive, even though the rest of them weren't yet actually built, just being present in the queues).
Yes, you need to have 3 in existence, so you have to completely finish 3.
False. You need to have 3 in the queues already, irrespective if they are already built or not - at least for my case (BTS 3.19 modded with K-Mod 1.44b). The failgold happens once the (no. of missionaries in the queues + the missionaries in existence > the "legal" no. of missionaries). For example, in my case now, I have 4 Mining Inc. executives instances (each with the '*' sign, aka 'to be built indefinitely') in the queues of 4 cities, one instance per city. The failgold happens next turn at my 2nd executive built, even though I effectively built just 2 of those 4, as the other 2 are lower in the queues (so they don't get built all at the same time / turn). Why? Because the 4 in the queues + the 2 in existence > 5 (the "legal" no. of executives to be produced in one turn in the game).
I don't know if I was clear enough, or if someone reads this, considering it's an old thread, but that's just my experience with this. I don't think it's the "fault" of K-Mod, this probably happens in pure BTS as well (didn't tested though). I can provide the save for "proof", if needed.