the first appearance of Murdoc (in s2 ep "Partners") has flashbacks to the first time Mac meets Murdoc, Pete already knows him. This is also supposed to be the time Pete and Mac meet the first time (despite the s1 ep "Deathlock" saying Mac and Pete met in some situation with a camel - fans sometimes explain this away as being them lying but whatever).

first meeting flashbacks:
Mac is driving Jack's cab, filling in for whatever boneheaded reason Jack gave him. i think Pete hops into the cab and has Mac chase 'that woman' (Murdoc in disguise). Or whatever - something happens and they end up following Murdoc together and Mac foils Murdoc's plans.

episode main plot:
each of the 3 guys gets an invitation to meet at the junkyard and bring specific items with them. Peter and Mac think Jack set it up until they start going through the stuff in Jack's old cab that is still sitting in the junkyard (apparently 7 yrs later). Jack is late showing, but apparently Murdoc doesn't care - b/c he hauls the cab w/ Mac and Pete inside off to the middle of nowhere where he plans to blow them up.

obviously Murdoc's had a brainfart and has forgotten that MacGyver could get out of being sealed in concrete with a piece of fishing line and a bottle of bubbles, b/c Mac gets them out and then Murdoc blows his own self up when he drops his bundle o' dynamite.

then Jack bebops in all late with some flowers like 'hey guys!' and Mac and Pete make this face :/