Some common mistakes are:

• Low C# to D# trill on flute
• Harmonics in the first octave
• Low C and C# on piccolo
• Percussive effects in the second and third octave: key clicks, tongue or lip pizzicati, tongue ram. While these are not mistakes per se, they are not very effective outside the flute’s first octave.

see also:
Writing for Students
Pet Peeves