Is my girlfriend's Saturn V drawing technically accurate?

The first thing to check is the fins. The Saturn V didn't have any. No fins at all, actually, unlike a lot of rockets people grew up seeing in cartoons. If she added fins at the bottom, that's the one clearly wrong detail, and it's an easy fix or an easy artistic choice to defend. Plenty of fictional rockets get fins because they read visually, so nobody's going to fault her for it, but if she wants accuracy, lose them.

On the black and white pattern: the real rocket had a specific roll pattern. Most of the body was white with black bands in certain spots, the most noticable being around the section between the first and second stages, a black band near the top, and black covering the aft skirt of the third stage right above the engine section. There were also USA letters painted large on the first stage. If her pattern looks like alternating black and white rings all the way up, that's more 'generic rocket' than Saturn V. If she's got sparse black bands on a mostly white body, she did her homework.

Proportions matter a lot with this rocket. It was extremely long and skinny, over 360 feet tall, so the nose should be a fairly small capsule and escape tower perched way up on a very long tapered body. If it looks stubby, that's the most common error I see in artwork. At the bottom there should be five big bell nozzles clustered togehter, four around one in the center, not a ring of many small ones. As for the tower, the launch umbilical tower stood to one side with swing arms reaching over to the rocket, and it stayed standing after liftoff, so if she drew the rocket clear of the tower with the tower intact behind it, that's correct.

One fun detail she coud lean into for the night scene: Apollo 17 was the only Saturn V launched at night, and the five F-1 engines lit the whole coast bright as day. If her glow reads like sunrise, that's honestly accurate.

I built a scale Saturn V a few years back and the thing that surprised me most was the smoke. Real launch photos show the exhaust blasting sideways out of the flame trench at the base, so you get these huge horizontal clouds rolling outward, not a soft mountain of smoke piled up under the rocket. If her smoke reads like a cartoon cloud sitting under it, that's an easy tweak that whould sell the whole piece. Second thing I'd have her double check is that little launch escape tower on the very tip. It's tiny but it's the detail people who know Apollo always look for first. And yeah, tell her to pull up Apollo 17 launch photos, that's basicly her exact scene alredy shot for reference.

The escape tower up top is another thing worth a look. It's that skinny little lattice spire sitting above the capsule, and a lot of artwork leaves it off because it looks fragile. When I drew one for my dad a while back I kept botching it til I printed out a NASA photo and worked from that instead of memory, night shot and all. Honestly that was the whole difference, working from a real photo rather than guessing.

For colored pencil on a night scene like hers, a white gel pen was the trick for me. The engine glare and lit-up smoke edges pop way better layered over the pencil than any white pencil I tried.

This thread made me go watch an old launch video and I was surprised how slow it leaves the ground. It kind of just rises, like a building lifting off, not a fast zip like in the movies. So if her drawing shows it only barely clear of the tower with the glow already spreading everywhere, that might actually be right. One thing I keep wondering about though, does the flame look more orange or more yellow white from a distance? I always picture it like the sun but I might be mixing that up.

Update: she fixed the fins first thing. Turns out that was the big one, the real rocket never had any. She also pulled up launch photos after reading the bit about the smoke rolling sideways out of the trench, and redid the cloud shapes completly. The escape tower is staying, she found it on a NASA photo like you suggested. She's actually relieved it wasn't the black and white pattern.