When the drill comes up through the floor of the vault, it leaves several large chips at the edge of the hole as well as some debris; yet when the heating apparatus comes up through the floor, the edges of the hole are perfectly smooth and there is no debris.
The tape recording in this episode is on a 4-track tape cartridge, but when Jim is looking at the picture of Krim you can see the reels of a large reel-to-reel player turning behind it.
Melting the gold in the vault at over 2200°F would very likely cause severe damage to the concrete in the vault. Concrete will begin to suffer structural damage above about 600°F.
Barney is funneling molten gold into molds through a hose with a metal nozzle. The gold is at 2200 degrees Fahrenheit yet he is not wearing gloves while handling the nozzle.
If Barney and Willie were lifting/transporting 4 cubic feet of gold (probably a low estimate) hanging in front of the truck, it would have tipped over, as there is no ballast in back of the truck to balance it out. 4 cubic feet of gold weighs approximately 4800 pounds - probably close to the weight of the truck.
As Willie drills up into the gold vault from the tunnel, there is an initial bit of rock debris that falls from the drill bit, but after that there is no dust or rock debris falling from the drill bit.
Jim changes the magazine in Colonel Krim's 45 to one that has two blank rounds on top. When Krim aims at Rollin, the gun fires and cycles twice. In real life, blanks would not have the inertia to do that. It would just jam. A semi-auto must be modified to shoot blanks.
When Colonel Krim shoots Rollin, he shoots twice. Then, using the same pistol (without reloading), he shoots Karl, killing him. The team could not have known exactly how many shots Krim would take at Rollin, so could not have known precisely how many bullets to replace with blanks. However, during the planning scene, Jim says of the two blanks "After that, you're on your own," showing they all understood the risk.
In order to steal the gold the IMF team heats the vault hot enough to melt the gold bars (2200 degrees F). Yet, immediately after getting the gold, they spray paint over the walls and floor. The paint would burn, or at least blister if sprayed on the heated walls. When Krim enters the vault he doesn't notice the heat or the smell of paint. It would take at least 36 hours for the walls to cool to room temperature.
While interrogating Rollin, Krim clutches a rather small coffee cup (which he seemingly perpetually drinks from). A close up of the cup reveals the half full cup of "coffee" is actually painted inside the cup - it does not slosh around when he moves.
When Phelps goes to unlock the car in the opening segment, the driver's side window is open, making it very easy for anyone to get into just by reaching in and pulling up the lock button.
Wille wears thermal protective gloves to lift the ingot molds, yet Barney is using his bare hands to hold the spigot which is pouring the molten gold into them.
After the gold is melted and extracted from the vault, Barney activates a spray mechanism that paints the floor with what seems to be a shade of tan. It is far-fetched that Krim and Gruner failed to notice the difference, and also that the paint is likely still wet.
The entire plan for removing the gold from the storeroom depends on the room having a smooth floor that slopes cleanly to a single point sufficiently low for the melted gold to flow cleanly out a drain hole. Such a floor is extremely unlikely to be found in a central African mercenary camp.
After Rollin knocks out the mercenary following him he appropriates a truck for Barney and Willie to transport the gold, and then drives it freely away. Such a secure compound would likely have guards posted at various points that would have noticed the truck leaving.
Barney uses a Geiger counter to detect the ball that Jim drops in the vault. Willie drills thru at least 8 feet of rock and then pockets the ball. To be detected thru so much rock, the ball would need to emit high levels of gamma radiation. Jim and Willie would receive dangerous doses just by touching the ball, much less carrying in their pockets.
Willie should be wearing eye protection while looking up into a hole he's drilling into the concrete.