Which has greater N-O bond length: NO or NOCl?
Also relevant:  the nitrogen-chlorine bond lengths:

$\ce{NOCl}=196\text{ pm}$ Wikipedia

$\ce{NCl3}=176\text{ pm}$ Wikipedia

The oxygen in nitrosyl chloride is donating its lone pair to the antibonding orbital in the nitrogen-chlorine linkage, weakening that bond but adding more pi bonding between nitrogen and oxygen to become like a triple bond.

If we were supposed to compare bond lengths using "simple" principles of bonding, this is a poor choice.  Nitrosyl chloride presents more than meets the eye.