Inconsistency + a minor goof
I watched the movie recently for the first time and enjoyed it, but I don't get one thing. Why is Nick inconsistently invisible in some scenes and visible in others (I mean to us, the viewers, not to other characters in the movie)? An example of the latter is when he takes a taxi - by that point in the movie he's already invisible and wearing his original clothes that also became invisible but not wearing any makeup yet, so why can WE see him in that scene?
As for the minor goof, I recall at some point Nick says he can't sleep because his eyelids are invisible to him. Why couldn't he just blindfold himself with a band?