Parents are concerned that children who have trouble in school will 'fall through the cracks' in the school system. [=will not be given the help they need; will graduate without anyone noticing that they are unable to do the work]
The program is meant to help workers who may have 'slipped through the cracks' [=who may have not been included in other programs] because of their age.
You ought to 'get cracking' [='get going; get moving'] on that assignment. [=you should start working on that assignment right away]
(..) the hours, so technically we still have... ten left to find our Mr. Otterton. And that's exactly what we're gonna do. So if you'll excuse us, we have a very big lead to follow and a case to crack. Good day. Officer Hopps. Thank you. Never let them see that they get to you. So... (..)2016 Zootopia