The first challenge is one issued in 1990 by ex-preacher Dan Barker. The full explanation can be found here. He simply asks for a plausible description of events that occurred between Easter morning and Jesus’ ascension into heaven. The chronology must fit all the details recorded in the four gospels and a few other places in the Bible. The claim is that this cannot be completed without contradicting at least some biblical details. This challenge has been taken up by a pastor, Stephen Kingsley, in his book The Easter Answer (to which Dan Barker responded) and some websites such as this one. So is there any challenge left? That depends on your view of the flexibility of the Biblical text. If this particular part of the Bible doesn’t strike you as contradictory, there are numerous other contradictions listed in The Skeptic’s Annotated Bible or the associated website.