Red flag No. 6: Testing is an afterthought
Testing is essential to project success. Whether it is unit testing (which tests one facet of the system) or integrated testing (which tests all components, including existing interfacing systems), it should be done by current employees along with a testing script. The testing script should include all inputs, step by step, that testers should make. And you should detail, ahead of time, what all outputs should look like.
Testing data and processes should vet all scenarios, including good and bad data. Sometimes results from known bad data are more interesting than those of a desired outcome. Testing should include load tests to see how the system and network respond under heavy utilization, and testers should understand expected outcomes and be expected to report all deviations.