Well I'm not usually an Arsenal supporter, and I usually get anoyed at Arsenal's players such as Reyes, Van Persie, Pires, and Fabregas for their diving and acting, but this is my opinion on these situations.
As for the Reyes coming back on to the pitch...
It was extremely poor sportsmanship, it was disgraceful. However, he has a right to crawl wherever he wants to. As far as I know he wasn't complaining about Real Madrid not playing the ball out, he was just injured. He hasn't really committed an offense except for unsportsman like behaviour, and that certainly doesn't warrant a red card.
The Beckham/Lehmann penalty shout...
Lehmann went down to get the ball, he did so, but it hit Beckham. Then what was Lehmann supposed to do? Shrink to the size of a fly? His body is still there, Beckham for me, just ran into him, and I'm not saying he was looking for a penalty, because he didn't even appeal, it was just basic physics. It would have been a very very harsh decision to give a penalty.
Cicinho's acting...
When Fabregas was booked, Cicinho's legs were already dragging (as if he'd been clipped) before he'd even touched Fabregas, and then when he threw himself into Cesc, of course he fell over. It's like the Beckham incident, Fabregas was only running, he didn't stick out a leg or anything, Cicinho decided to go down too early. Then he definitely had moments of dramatization on injuries but it seems a lot of players in the Spanish league do this, and there are definitely numerous players who do it in England such as Ronaldo, most of the Arsenal squad (well some), etc... so I'll leave that alone even though I hate it.
Overall officiating...
I thought it was fairly weak. The ref seemed to blow up for some baby touches, like he thought football was non-contact. If Bobby Moore were playing he'd be laughing his head off at some decisions like this... I don't think it's always the referee's fault, I think it's got to do with people higher up in FIFA... taking away the physical side of football... but oh well, the referee wasn't too bad.
There were definitely some poor offside decisions, but that comes in every game.