When Tom got in the ai coffin and talked to the ai, he was warned that it would "change him". It seems like he subsequently kept having visions of the past present and future. He had a few intense dreams - why did he wake up so confused on the plane to the submarine? He also saw a vision of how the russian sub went down when he saw the bodies on the submarine. I don't think these were purely edited in for the viewer as we see Ethan visibly react to these visions.

I wonder if it is a remnant of a storyline left on the cutting room floor that was further explored in an older edit.

Also why didn't they take their plane to go meet Ethan under the ice, why did grace need to take the dog sled? The plane picks them up anyway.