When Rick grabs the note from Balowski he doesn't do so cleanly and it is in two pieces. On being handed on to Mike to read out the note is entire and relatively uncrumpled.
When Vyvyan does his finger trick, you can clearly see tubes going into his gloves to provide the blood. Some say this is a mistake, but others say it's part of the practical joke kits he uses because blood was meant to spurt out of his hand when he cut the fake finger off. It's a goof only if you want it to be.