I typed in "Have a look, Matej, it is not possible!". Duolingo marked my sentence as incorrect because I didn't put a caron above e in Matěj, and said that I "used the wrong word". Should this really be considered a mistake? If not, is it fixable?
Yes. We should have Matej available on the English side everywhere (as well as Frantisek and Zofie...) but at times we missed few, so keep pointing those out. We fix them as we come across them.
Would "hele" work here instead of "podivejte se"? Just curious if they have the same meaning/usage.
Hele is among the accepted translations.