I'm in the midst of rewatching the finale from the I Tunes download, and there are quite a few time cues in the first part of the Hiroshima-Osaka leg that help point to the flights taken by the final four teams.
First, we're told about Rachel-Dave's release time in Cochi, 1:51 pm. Since teams in India have to purchase their tickets from a travel agency (this goes back to TAR 1, remember) before they arrive at the airport that should help narrow down when the teams left. It should also provide information as to when Phil and his camera crew left Cochi because of the daylight for Phil's stand ups in Japan (He had none in Hiroshima and his first one was the game show in Osaka). The travel agent for Rachel-Dave quite clearly says that their arrival in Hiroshima would be at 8:10 the next evening, and that it was the fastest flight available.
We don't get any help from the Amazing Red Line on the Bing globe, but we get some clues as to the arrival time based on the fact that teams had to buy tickets to take a shuttle bus to the train station to get to the island, and had to buy tickets at the train station (several edits tell us 10:20 was the next departure, and then a 21:55 (9:55 pm) time on a digital clock in the train station.) Then we also have the time of the last ferry departure that evening and the first departure the next morning; we ought to be able to work backwards from this to see if just one flight fits all of this together. (I personally suspect it does; and it should be possible to get an estimate of the time it takes the shuttle bus to get to the train station.) I'm basing this on what had to be done in other seasons at times to reconstruct timeline elements, but I think it likely it'll be possible to do it.
(I'm not going to rub it in over the teams flying into Japan at Hiroshima or Osaka...it made sense to me for them to do so this time, once we knew about the Osaka pit stop, since the show has a pattern in recent seasons to pick airline flights that have very few or only one option for the teams, and to manipulate the pit stop releases to force those options while giving production a head start to the next destination. It avoids a lot of bunch in mid-leg and artificial HOO.)