So, the aim is to increase the employees' buy-in to the code review process? A teacher friend of mine used to use a technique known as "Doggies" to encourage her class to pay attention, ask questions and generally participate. "Doggies" were cardboard tokens (with a cartoon dog on) that she made and handed out during a lesson for good answers, positive attitude, etc, etc. At the end of the lesson she had a lucky-dip bag containing random sweets, stationery items, etc. One "Doggie" entitled the holder to one dip in the bag. She found it increased concentration no end, because the class enjoyed the game aspect of the prizes. Of course, her decisions to award Doggies were somewhat arbitrary, and depended on the pupil's "normal" behaviour.

Not sure that this necessarily works in your case. If you have a timeliness problem, sounds like you need better project management and better understanding of the need for code reviews and suchlike from your fellow coders. It's a classic management problem, how to get people to do a task that they don't particularly enjoy. I know I go on about this a lot, but go and read the work of W Edwards Deming (start wth deming.org) and go on from there. I can give you a quiok primer if you want.