Continuity mistake: At the bank, we see Curry empty the jewel bag onto Binford's desk. Ten stones fall out. But in subsequent close-ups, there are twenty. Despite this, Heyes asks Binford to write a receipt for "ten little stones that sparkle and glitter a lot."
Continuity mistake: Having borrowed the valuable uncut stones from Soapy, Heyes and Curry don't seem able to keep a very good accounting of them. Ten are sent out for evaluation, and twenty-one more are used to salt the fake diamond field. They should be returning thirty-one nuggets to Soapy at the end of the con game. Yet there are fewer than twenty diamonds on the table when Soapy empties the cloth bag.