"The eyes look like an apple."
Yes I think it is. But the solution they gave me is wrong I think : "Die Augen sehen wir ein Apfel aus." - Here, "wir" should be "wie" I think.
... Then, after "aussehen" you use Nominativ, because it's like putting subject and object on the same level?
Did I already say that I don't know any German?
I do not think so, i think it is a new sentence: Die Augen sehen aus wie ein Apfel SIEHT
(but you can omit it)
Does this sentence make sense? Does it really mean "the eyes look big and red" or something like that, or is it an idiom that means something else?
yes, it does literally mean 'the eyes look like an apple' - strange form of compliment, I agree ;-)
Can it be "Die Augen blickt wie ein Apfel." ? Is blicken "look at" rather than "look like"?
'Blicken' means 'to look' in the sense of 'to glance'. Technically, it could be "Die Augen blicken wie ein Apfel" meaning they stare at you just as an apple does. If the apple were an alligator (I learned from your profile that you're from Florida), it might make sense.