Hey AwSnap,
Looks like I'm a bit late to this party. Anyway, here are my thoughts for what they're worth.
I would expect the JW to use one or more of the following:
1) The apostles didn't correctly understand "The Kingdom." They thought that Jesus was going to restore Israel to its former glory. (for example, in Acts 1:6 they asked "Lord, are you restoring the kingdom to Israel at this time).
2) Similar to #1, some disciples thought that Jesus said that the apostle John would never die. (John 21:20-23; note that verse 23 mentions a rumor that spread among the early Christians that John would never die)
3) The prophet Nathan made a statement that could be construed as false. This is a (IMHO very weak) argument that some JW apologists use. If you read 2 Samuel 7:1-3. King David tells Nathan that he wants to build a temple for God; Nathan says go ahead, for the Lord is with you. Well, in verses 12-13, God tells Nathan to tell David that David's son (not David) will build the temple. So, some JWs argue that Nathan made an incorrect statement to David but still functioned as a true prophet of God.
Well, if you actually read the verses, Nathan didn't say that David would build the temple. He merely said, do what you want; God is with you. It's a major stretch for JWs to compare such vague, general statements with Rutherford's "indisputable conclusion that millions now living will never die."
And, for all of these examples, it's important to note that there is not a shred of evidence that these folks required their fellow believers to accept their speculations as doctrine upon pain of shunning and excommunication. Rather, #1 and #2 seem like examples of the kind of rumors that pass through the congregations. To me (and anyone else who looks at it objectively), there's a huge difference between rand-and-file members passing rumors and leadership promulgating false doctrine.
Shouldn't the leadership have some responsibility and accountability? That's what gets to me. The WTS leadership are like politicians--they refuse to accept responsibility or accountability. Everything is someone else's fault. For example, when some rank-and-file members made bad decisions around 1925 or 1975, the Society blamed them for being over-eager. Never mind the fact that the WTS beat the drums and built up the false expectations. But, of course, the WTS laid the blame at the feet of the victims.