One of the later seasons has an episode called "The Photographer". A famous magazine photographer is actually an enemy spy. Something to do with his parents having been accused of spying and executed by the U.S. Holds a grudge. He has a underground nuclear bomb shelter on his property. Can't remember all the specifics but they trick the photographer into thinking a nuclear exchange has taken place. First they block regular radio/tv broadcasts to his house and send fake newscasts that only he can receive that nuclear war has taken place. Naturally he heads for the bunker. Prior to this they went into the bunker and rigged the radiation gauges, etc. to give readings consistent with a nuclear blast. Once he's in the bunker they do something to make the ground shake and such. The bunker has a periscope so those inside can recon the situation on the surface. The MI sets up fake scenery that resermbles nuclear destruction in a 360 around where the periscope sight exits the ground. You get the idea.
Once they tricked a guy into thinking they had a perfect counterfeiting machine. Put in a real bill and it spits out a perfect replica. Actually Barney(Greg Morris) is inside the machine with a stack of real money to push out the slot.
"The Killer" guest starred Robert Conrad as a hitman who is suppose to assassinate somebody important. They pick him up at the airport in a fake taxi. He is suppose to go to a certain hotel. The MI team converts an abondoned building into a fake hotel(with just one room) and take him there and he believes he is at the real hotel.