I think the crew jumped the gun on this one. If the aircraft was outbound as the TOI report states, they could have just returned to the gate instead of ordering an evac.
And what's the bull about the slides not opening on the overwing exits. There are no slides there (see diag. below), you've just got to slide out over the back of the wing. The slides are located only on the doors.
It's simple. The wings act as slides. Slides are required on the other exits because there's a sheer drop and you're bound to break a few bones trying to jump about 10ft or so below. If passengers sustained injuries while being evacuated from the slides or the overwing exits, it was probably a result of a mixture of over excitement and panic in the wake of the situation.
Does anyone have an idea about whether this a/c had just returned from maintenance? Could be storage oil burning off and smoke penetration through the airconditioning. Most likely a molehill rather than a mountain.
737 evacuation diagram
