> I have played a guy who quickily send an ifv with a dog inside. The dog jumped into my barrack and then all his soliders and even the paratroopers being upgraded afterward.
> It must stressed that it is very early, no science lab and therefore the jumping in "stuff" is and must not be a spy. Does anyone see that? Some form of new trainer? The upgraded rocketeer and paratroopers is difficult to fight.
That must be a spy... you must have missed his science lab somehow. I mean, if it's early in the game you might simply not have discovered it.
You can easily identify spies though. Just look at the speed of the dog. dog-disguised spies don't go faster, which means you should see the dog jump in slo-mo.

C&C Meets Star Wars - the only TC for C&C1 ever made.