There should have been two blood stains on Mickey Blue Eyes chest at the end: one that ruptured prematurely and the other following a shot by his fatherinlaw. There was only one visable stain after the shooting.
shareI think he switched shirts with his boss in bathroom
shareI know that this post is months old but since my kids love this movie we've been watching it almost every day for 2 weeks straight and I can say that yes, he switched shirts with his boss in the bathroom before the speech. Actually he didn't switch, he took Mr. Cromwell's, cause when they come out of the bathroom Mr. Cromwell has no shirt on under his jacket.
shareI thought about that too - he HAD to switch shirts (and with all the 'back up' he had from the FBI, it wouldn't be that hard....) because what groom is going to go through the reception with blood stains on his chest? I did think it was funny that his boss thought it was a party trick.
shareNope. After he accidentally ruptures the first squib, he changes shirts with his boss from the auction house. (Although the shirt change is not explicitly shown, it is clearly implied from the the two of them in the bathroom stall and then the boss later having no shirt under his tux jacket.)
So his shirt at the end would only have one bloodstain.