The unit word here can be either 個 or 部 我想看一 個/部 廣東話電影。 If it is a traditional Chinese opera, the unit word can be '齣' as in "一齣戲." '出' and '齣' are pronounced the same way, but '出' is not to be used here. I want to = 我想(要) (here '要' can be omitted)

我想看一齣粵語片

我想看一（出）廣東話電影 我想 = I want （to）