Here's my take on what the preview may reveal (of course I could be totally wrong)1. After the closeup of Blake/Paige, we see a guy hitting a chunk of ice with a hammer. It looks like a choice between chipping away at the ball of ice, or melting the ice. Maybe the next clue is inside the ice. Something tells me this is Chex hitting the ice.
2. Chex in their vehicle in Alaska.
3. Tara getting a kiss. We know Chex and Twil are on the same flight.
4. What looks like Wil burning the ice.
5. Wil diving for the clue in Hawaii, with Tara encouraging him.
6. Blaige on their boat in Hawaii. Looks like Blake has already dived for the clue. Blake is reading, and Paige is looking back (at the competition?)
7. Chex on their boat in Hawaii.
8. Will doing a crazy laugh on their boat. This appears to be before he dives. His hair is dry and he's fully clothed.
9. Two or possibly all three teams diving for their clues. Looks like the yellow container on the far right is either all the way open, or is more opened than the other two. The center person appears to be Blake.
10. Blake immediately after getting the underwater clue. He slams the mask down and is pumped up, and Paige is smiling.
11. Wil and Tara in Alaska. Tara moans loudly, and Wil looks like defeat.
12. All three teams running through what appears to be the Alaskan airport. People walking the other way have heavy coats on. If this is true, we know they all get the same flight from Hawaii to Alaska.
13. Wil and Tara arguing next to the ice chunk. Tara says "Do it! Go!" Wil responds "Shut Up!" Notice in the background, an ice chunk is broken in half. We know at this point that Twil are not in first.
14. Paige driving a GMC Jimmy in Alaska.
15. Blaige running through a pineapple field in Hawaii on what appears to be a maze of dirt roads.
16. Chex entering their vehicle in Alaska. The passenger has ice chips in his hat. Maybe he used the hammer to get the clue.
17. Blaige EXITING the airport, possibly in the final city. Lighter clothing, definitely not Nevada. Blake is hailing a taxi as they run out the door.
18. Chex running down the street. It looks like he's lost.
19. Blake exiting a TAXI on what appears to be the same neighborhood that Chex was in. Looks like he knows more where he's at.
20. Twil in the airport at Hawaii (Hawaiian airlines ticket counter in the background). Wil exclaims how Tara lost the clue. Since it looks like they were even in Alaska, I'd say it causes no loss of time.
That's what I see. Who knows though.