Try blocked Pitots on takeoff in the sim and see how many crews lose control of the aeroplane before they have a clue whats happened.
I don't know about blocked pitot heads because that should normally be picked up during the take off roll during the 80 knots (Boeing) or 100 knots(Airbus) IAS check, thus permitting an early abort if required.
The really nasty gotcha (in the 737 Classic anyway) is a blocked captain's static vent. During the take off roll until airborne, flight instrument indications are normal. After lift off the captain's altimeter does not move; nor does his VSI. This is where the captain has to be careful when the first officer calls "Positive rate of climb" on his side that the captain doesn't automatically reply "Gear Up". Because he does not have the usual indications of positive rate of climb on his side since his static vent is blocked.
Soon after in the initial climb (about 30 seconds after airborne) the captains ASI needle starts to slowly go backwards and indicate a speed loss due to its blocked static vent. As the airspeed needle continues to fall back, it triggers a spurious wind-shear warning and a few seconds later, off goes the stick shaker as well. The stick shaker of course is giving a false warning and the first tendency as a startle factor (seen in the simulator, anyway) is to lower the nose.
The fix is to disregard the spurious warnings and maintain the correct climb attitude for the configuration, check the correct N1. A quick check of the ground speed read-out will give the pilot a confirmation which ASI is untrustworthy. That is one reason why a glance at the expected ground speed read-out at the 80 knot or 100 knot call is a useful back-up against an unexpected erroneous airspeed event.
The blocked static vent can cause real confusion initially; which is why the pilot needs to fly expected body angle and N1 for the state of flight until trouble shooting sorts things out. During the sorting out process in the climb, be careful not to overspeed the flaps as it is all too easy to concentrate on various aural and visual warnings and ASI readings and forget that the aircraft is still accelerating fast.