Many skeptics point out that Matthew and the writer of Acts (most likely Luke) contradict eachother regarding how Judas died. Matthew states that he hung himself. Acts says that he fell headlong into a field and his guts spilled out. What is not said what actually killed him the hanging or the fall. This means both descriptions could have happened even though only one of these events would have actually killed him.
There is no contradiction here because the account in Acts is not pointing how Judas died, but where he ironically ended up. You see the field Judas' body fell in after he hung himself was the field the pharisees bought with the money Judas received for betraying Jesus. Peter mentioned it this way in that he was pointing out how Judas would rot in the fruit of his own sin.
Judas hung himself and at some point the branch he hung from broke allowing his body to fall. He most likely landed on some rocks or something that would have caused his guts to spill out of his body. There is a second illustration provided here by Peter for us to discover. Jesus has many nicknames and one of them is the Branch. Judas killed himself physically and spiritually by breaking the branch and falling into his own sin.
So you see this is obviously not a contradiction, but a teaching illustration meant to remind us of what Judas did to himself by betraying his savior and what will happen to all who reject Jesus. Those who claim this to be a contradicction have not really read the accounts and thought about the two perspectives. It is interesting how skeptics will scoff whether the account is identical or harmonized. Skeptics are looking for a reason to accuse, they are not seeking truth.