Assuming z-axis as the inter nuclear axis, the incorrect statement is

‘sp²’ hybrid orbitals are oriented 120⁰ to each other 

‘sp’ hybrid orbitals are formed by the mixing of s and p_x orbitals

d - orbital involved in sp³d hybridization is d_z²

In ${\mathrm{NH}}_4^{+}$, hybridization of ‘N’ atom is sp³