זֹאת עֲשׂוּ וִחְיוּ
It is of utmost importance that the word עשו be pronounced properly and not עָשׂוּ . The word is meant to be a command but if improperly pronounced, it is a past tense verb. Basically, it is supposed to be "do," not "did."
This is one of those examples which can really be tough to call depending on the בעל קריאה. I have heard some who literally do not differentiate between a קמץ and a פתח. There isn't really much you can do in such a case. For those who do differentiate properly, it is important to keep on eye on constructs like these. This is hardly a unique case. Later in the פרשה we have מַלֵּא אֶת אַמְתְּחֹת הָאֲנָשִׁים אֹכֶל מ"ד:א, as well as וְאַתֶּם עֲלוּ לְשָׁלוֹם אֶל-אֲבִיכֶם מ"ד:י"ז at the very end. And in next week's פרשה as well: אֱמֹר אֶל אַחֶיךָ זֹאת עֲשׂוּ and וְאַתָּה צֻוֵּיתָה זֹאת עֲשׂוּ.
Please post additional examples in the comments. If you point to the פסוק, I can insert the Hebrew.