Hehe, there are several glitches within the game. Some is detectable, some aren't.
The problem is, those who knew how to do them is gone, and thus (sadly?) the knowledge has been lost.
Lad, you should know better then that. Old gamers never die, we just take vacations for a while.
As to the Wall glitch, there is actually more then one and they have been around since the beta's of the game.
1. Occurs when the Tube layer is destroyed while making a wall.... this one is the worst because the wall is actually built, can not be destroyed, can not be unbuilt, but it can not be seen and can not be driven or shot through by most weapons. (EMPs, RPGs, ESGs, Thors can shoot over it.)
2. The other one occurs when for unknown reasons a wall has sustained alot of damage, but not quite enough to actually destroy it. However the game has decided on its own volition to allow the wall to be destroyed as it expected it to take more damage with in the next .00001 to .00002 seconds from say a thors hammer firing in close proximity to it. (other weapons or damage has been known to apply on occasion.) This damage does not occur because in the space of that time the player has manually re-targetted a new structure, section of wall, or vehicle.
3rdly and last the Bulldozed wall. This is actually a glitch and it occurs to tubes too. A bull dozer for whate ever reason suddenly decides to bulldoze a tube or wall section. This wall or tube disappears and 99% of the time is no longer counted as present, however on rare occasions the cell remains as a very real presence that can not be destroyed, targetted, or other. Tubes found in this condition will still link to other structures, but can not be built over or connected too or off of.
The convec thing likewise has been around for a while. No offense Hacker, but it was reported hundreds of times to Dynamix and later Sierra and no one ever bothered to fix it. I am fair certain that the Wall gltiches and the Minor Convec glitches deal with the barely useful AI section of the engine. It seems to "expect" something to occur, and at the last second that changes, and it never changes its expectation.
I am reasonably sure that either these are unfixable items, or to fix them would require too much work, or fixing them may irrevicably damage some item in the game.