Inverting Schmitt trigger using uA 741
I'm assuming you have +/- 15 V power supplies and for that level of supply the input common mode range is between +/- 12 V and +/- 13 V.

Any signal outside these limits and the performance guarantees in the data sheet are out of the window. You appear to be injecting a peak to peak voltage of over 30 V (according to your o-scope).

Now I don't mind if you blow the 741 up (and all the rest in the universe because they are really crappy come to think of it) but you might care so, respect the information in the DS or you may damage it.

The DS says the absolute maximum input voltage is +/- 15V. It also says this: -


  7.3.1 Overload Protection - The LM741 features overload protection circuitry on the input and output. This prevents possible circuit
  damage to the device.


This probably means that inputs approaching the "out-of-bounds" area will be somewhat clipped.