"We will watch a Korean movie on the weekend."
I think it may be optional (not sure because I used it in ym response) but the huì emphasises that it is something you will do at a later date.
Also correct. I believe that developer only considers the literal translation.
It is common for one to treat 這個 as "the", even if it literally means "this one". IN reverse course, such answer is also accepted.
In this case, your translation (time-subject, subject-time; vice versa) is good to go for.
I'm not sure if it is strictly necessary, but duolingo wants you to use 会 before 看.
"我们这个周末会看一个韩国电影" Why is this wrong? Should I use ”一个“ to specify A Korean movie?
Character for Can also means will?