From what I've gathered in twitters and blogs of people who actually watched live both the election proceedings and NHK's reporting on the election (I watched only the election, live on the net), NHK repeatedly reported the totally wrong information about the number of votes that might go to Noda between the first round of voting and the second (final) round of voting.
There were close to 90,000 people watching the netcast of the election, with many of them also watching NHK.
The sequence is something like this:
1st vote ended. The result: Kaieda 143, Noda 102, Maehara 74, Kano 52, Mabuchi 24.
2nd round of voting started. Then about 15 minutes into the voting that took about 30 minutes, NHK reported: "Mr. Mabuchi instructed his supporters this morning to vote for anyone other than Kaieda [if Mabuchi loses in the 1st round]."
NHK also said "Kano instructed his supporters to vote for Noda, so did Maehara." NHK was practically predicting the landslide victory of Noda in the 2nd round. They were still voting, and the NHK report was conveyed by the reporters covering the election to the representatives.
2nd round ended. The result: Noda 215, Kaieda 177. Difference was 38 votes.
4PM: Special NHK News - "What we reported earlier about Mr. Mabuchi was wrong. He did not instruct his supporters to vote for anyone other than Kaieda; he told his supporters to do vote FOR Kaieda because Kaieda's policy on tax was close to his (they are both against increasing tax)."
Well, that admission was about 2 hours too late.
Despite the report, Mabuchi supporters are said to have voted for Kaieda after all. But the NHK's erroneous reporting may have swayed enough undecided voters in each faction, as all it took was to sway 16 votes in favor of Noda.
So, NHK may have ended up playing the "kingmaker" in deciding the next prime minister of Japan. Inadvertently or not, I do not know.
I do remember, after the election, PM Kan was all big smiles on the stage with 5 candidates. He must have been so happy to see the candidate backed by Ichiro Ozawa defeated.