"Κοιτάζετε τους εαυτούς σας!"
Translation:Look at yourselves!
No - "Κοιτάζετε τους εαυτούς σας" would not be said in that scenario; only "Κοιτάξτε τους εαυτούς σας" would fit. You could add "Να" in the beginning, so that the phrase reads "Να κοιτάζετε τους εαυτούς σας", and then it becomes a suggestion or advice, something akin to "Look at/You should be looking at yourselves", or as I said in my previous post "Mind/You should be minding your own business". Not look after or take care of yourselves though - as HellasCad said, that would be "Φροντίστε/Να φροντίζετε τους εαυτούς σας".
look at yourselves
It looks fine to me, please file a report in such cases using the REPORT button or even a bug report (https://support.duolingo.com/hc/en-us/articles/204728264-How-do-I-report-a-bug-). It is often the case that people reporting rejected 'identical' answers have actually made a mistake, e.g. typed characters from both EN and GR keyboards, so please check carefully before doing so (I'm not saying this was the case here, just as general instructions).