This Bible contradiction is from the Skeptic's Annotated Bible.
He hanged himself.
Matthew 27:5 View context
And he cast down the pieces of silver in the temple, and departed, and went and hanged himself.
He fell down and died.
Acts 1:18 View context
Now this man purchased a field with the reward of iniquity; and falling headlong, he burst asunder in the midst, and all his bowels gushed out.