In a script, there are two categories of language: (1) words in dialogue and (2) everything else. (Words in a printed document like a ransom note are in the first category.)

(1) Words in dialogue (and ransom notes) should reflect the language of the speaker (or kidnapper).

From the point of the view of the movie VIEWER (as opposed to script reader), words in dialogue have no punctuation, capitalization, etc. A homonym misspelling (e.g. "to" instead of "too") tells the READER that the writer is carless or inattentive to standard grammar rules. Otherwise, spelling, capitalization, punctuation, etc. in dialogue can be used to give the READER (including actors) clues about how dialogue should sound / be delivered.

(2) Words elsewhere should be follow standard rules of punctuation, spelling, capitalization, etc. UNLESS the writer has a good reason to diverge from the norm (e.g. to create a voice for the narrator or to suggest rapid action with a series of one or two-syllable sentence fragments). Otherwise, go with standard grammar ("James Bond was lying on the ground" rather than "James Bond was laying on the ground"). As opposed to grammar--which changes gradually--there are plenty of "rules" for formatting, which can evolve more quickly over time. In my view, it's a waste of energy to focus too much on what's in or out, but who knows what some studio reader may think.

Writers should look at language choices as a source of power that makes their story more effective, not a set of rules that readers use to pass over their script.