By introducing geometrical optics approximation (GOA) solutions to a nearly extinct homogeneous nematic director, the effects of assembly misalignment and director fluctuation on light leakage transmittance are studied. Transmittance expressions including fluctuation swing are obtained for three misoriented cases: misaligned homogeneous case, misaligned analyzer case, and mistwisted nematic case. Except for the misaligned homogeneous case with second-order fluctuation, all the other expressions have a linear contribution caused by their own misorientation. From these results, the transmittance variance from fluctuation at a misaligned situation is more enhanced than that in the extinction situation. After introducing thermal average statistics, expressions for the average and variance of transmittance with fluctuation are given. A numerical estimation for these expressions shows that in the misaligned homogeneous case by 1°, the standard deviation of transmittance is 20% of its average.