I am currently writing a screenplay. Two teens enjoy their summer before real life sets in.
Now in the screenplay, a major plot point is the need to find a drummer for their rock band. They find one, but he dies. They find another one, but he also dies.
For the second one, there's about 10 seconds of a funeral Mass. Like many screenwriters (Zoe Kazan, Quentin Tarantino), I wrote a small role for myself as an offscreen priest presiding the Mass. Realistically, I'd only be saying an Our Father. It'd be very brief.
Would it be sinful? I assume that due to the nature of the film (think romantic comedy, i.e. 500 Days of Summer, Perks of Being a Wallflower, Nick & Norah, Ruby Sparks, etc.) I could not find an actual Catholic priest.