1. The scientists went to Antarctica for research recently. They were there on an earlier expedition, as well. Tomorrow Sam will select the movie, while Asim makes the popcorn
Explanation:
"recently" means in the recent past, went is past tense of go.
"as well" means they were there before in the past, therefore were is correct for past tense.
"Tomorrow" means in the future, therefore "will" is right for future tense.
Asim is making popcorn at the same time as Sam selecting the movie, therefore present tense is best.
2. Last night we talked about the concert, as we planned to go there next month.
Explanation:
"Last night" means past tense therefore "talked" is best.
They planned last night in the past, so past tense.
I hope this helps :)