A warning sign of a bogus schedule is magic dates.  Such dates tend be in two forms, the “when do you need it” form, and the “would you look at that” form.

The “when do you need it” form of magic date is the schedule date that miraculously meets the date management said they needed it.  To be fair, the team could have carefully manipulated the resources, features, and teamwork to make the date work out.  But even the best laid plans result in a schedule that only closely approximates the actual “needed by” date.  More than likely what has happened is that the team has felt the need to acquiesce to what they feel is a management-driven date, and thrown their estimates away.

The “would you look at that” form of magic date is the schedule for several disparate components that all miraculously converge to be completed on some date.  Realistically even under the best of circumstances, convergence of a number of components will happen at only roughly the same date.  If you find yourself looking at a schedule where they all magically make the same date, you should be very suspicious.