I believe that all Scripture is God-breathed. There are no errors in Revelation, only errors in interpretation. For instance, by dating the book around 90 A.D., people can't help but read the book with the pre-conceived notion that it is interpreting still-future events. However, the internal structure of the book itself supports an earlier authorship.
As I said, I'm still studying this, but I do believe that Revelation was written by John prior to the fall of Jerusalem in 70 A.D. First, Rev. 1:1 tells us that the apostle is writing of "things which must shortly take place." Verse 3 reiterates that "the time is near." Also, the book is written to seven specific, First Century churches. Why would John write to them of things that would not occur for untold millenia?
Dr. Ken Gentry explains more about dating the book of Revelation and determining the identity of the Beast:
But the vision causes John to wonder in quiet confusion. There is a difficulty involved. And that difficulty is that the seven heads have a double reference. We learn further that the seven heads also have a political referent: "And there are seven kings: five are fallen, and one is, and the other is not yet come; and when he cometh, he must continue a short space" (Rev. 17:10).(For the entire article, follow this link: http://www.forerunner.com/beast/X0002_Gentry_-_Beast_of_Re.html)It is surely no accident that Nero was the sixth emperor of Rome. Flavius Josephus, the Jewish contemporary of John, clearly points out that Julius Caesar was the first emperor of Rome and that he was followed in succession by Augustus, Tiberius, Caius, Claudius, and, sixthly, Nero (Antiquities, books 18 and 19). The matter is confirmed just a little later in the writings of Roman historians: Suetonius, Lives of the Twelve Caesars and Dio Cassius, Roman History 5.
The text of Revelation says that of the seven kings "five have fallen." These emperors are dead, when John writes. But the verse goes on to say "one is." That is, the sixth one is then reigning even as John wrote. That would be Nero Caesar, who assumed imperial power upon the death of the fifth emperor, Claudius, in October, A.D. 54. Nero remained emperor until his suicide in A.D. 68, a period of over thirteen years.
John continues: "The other is not yet come; and when he cometh, he must continue a short space." As the Roman Civil Wars broke out in rebellion against Nero, Nero committed suicide on June 8, A.D. 68. John informs us that the seventh king was "not yet come." That would be Galba, who assumed power upon Nero's death in June, A.D. 68. But he was only to continue a "short space." As amatter of historical fact, his reign lasted but six months ÄÄ until January 15, A.D. 69. He was one of the quick succession of emperorsin the famous era called by historians: "the year of the four emperors."