One of the big problems with replays in sitatons like this (offside calls and the like) is how do you interrupt the game to correct the call? For instance, if one pass should have been an offisde, but the ref doesn’t call it, then there are three or four back and forth passes which are legitimate, before the attackers score - do you then “reverse” the game, essentially cancelling out the 30-60 seconds of legimiate play back to when a offside should have been called?
Or if the ref makes an uncorrect call of offside, and it is overturend on review, how do you restart the game? A drop would do the attackers no good, seeing as the advantage of the attack is long gone, and the defenders will all be lined up and ready for the next attacker phase.
Unlike many other games where you have instant replay, football doesn’t easily lend itself to “resets” of the game, as the flow will be interrupted one way or the other.
I do, however, support an instant replay on penalties given, as penalties have such a huge impact on the game. This would probably lead to refs signaling for more penalties, because they know their decision will be double checked, and they would be less hesitant to influence the game erronously. This would have two positive effects, erronous penalty calls would be eliminated, and more of the “this should have been a penalty” situations would be judged as such.
Also, it wouldn’t interrupt the flow of the game, as the game has stopped anyway, and it would proceed naturally, either with a penalty kick, or a “free kick” for the defenders (and a appropiate yellow for the diving attacker, if apropiate)
ETA: Oh, as for off side calls, refs should be much more strigent with the “if you’re not absolutely sure, don’t call off side” rule. I’d rather they missed a few close calls in favor of the attacker per game, then cancel a legitimate goal.