CRITICALFailure Reference

Runway ML Hand & Finger Artifact — Pre-Generation Risk Reference

Technical Classification

Hand-Anatomy Topology Failure

Hand-Anatomy Topology Failure is the single most common rejection-worthy failure mode in Runway. Hands occupy a tiny fraction of training-data pixels relative to their anatomical complexity (27 bones, 14 phalanges, 5 metacarpals per hand). The diffusion model produces statistically plausible but topologically impossible hand structures: 4 or 6 fingers, knuckles bending the wrong direction, two thumbs, fingers fusing mid-clip. The failure is especially severe when hands are the prompt subject (musicians, surgeons, gesture close-ups).

How to identify this failure

✕Six fingers visible on one hand at any frame
✕Thumb pointing backward or duplicated
✕Knuckle bending in non-anatomical direction
✕Fingers fusing into a paddle shape mid-clip
✕Palm and back of hand swapping orientation between frames

Real generation examples

Prompt used

"Surgeon holding a scalpel, close-up of hands"

Failure observed @ 0:02

Right hand showed 6 fingers from 0:02 onward; knuckle inverted at 0:04

Prompt used

"Hands typing on a mechanical keyboard, top-down view"

Failure observed @ 0:03

Fingers fused into single mass at 0:03; reverted to 5 distinct fingers at 0:05

Documentation strength

If you need to escalate

VERY HIGH — Runway support treats hand failures as a recognised critical mode under their Anatomical Topology category. Refunds routine with timestamped evidence.

AVA is a pre-purchase prevention tool, not a post-purchase recovery tool. Platforms generally do not guarantee credit refunds for output-quality failures; goodwill credits are at each platform's discretion. The strength rating reflects how well-formed your support ticket can be, not a promised outcome.

Prevention + documentation steps

01
Score your prompt before you generate
Run your prompt through AVA's pre-flight scoring against the Hand-Anatomy Topology Failure pattern. Green light = generate. Yellow/red = rewrite using the suggested fix before you commit credits.
02
Capture Generation ID + timestamp if it failed anyway
Find the Generation ID in the URL or share link. Note the exact time when the Hand-Anatomy Topology Failure first appears (e.g. "failure first visible at 1.2s"). Timestamped evidence is significantly stronger than a general complaint.
03
Use the correct technical term in your support ticket
Describe this failure as "Hand-Anatomy Topology Failure". This term maps to a recognised internal workflow in the support system and routes the ticket to the right team.
04
Submit via the correct support channel
Runway has no direct email intake. Pro+ plan: open the in-app AI Assistant (help widget bottom-right of app.runwayml.com), describe the failure with the technical term, attach evidence. Free/Standard plan: human support isn't available — your channel is Discord #community-help with @On Call - Moderators.

Frequently asked questions

Will Runway support escalate credits for hand artifacts?

Yes. Submit the Generation ID with the technical term "Hand-Anatomy Topology Failure" and a timestamp showing the impossible geometry. Runway support classifies this under the same precedent as limb-artifact refunds.

Why does Runway fail at hands more than other body parts?

Hands are anatomically dense (small surface area, many joints) but statistically sparse in training data relative to faces or bodies. The denoising loss does not strongly penalise impossible hand topology because the model is under-constrained on hand structure.

Which Runway prompts are highest risk for hand artifacts?

Hand close-ups, prompts involving manipulation (typing, playing instruments, holding objects), and any clip with rapid finger motion. AVA's pre-flight scanner flags these prompts before you spend credits.

Catch it before you generate

AVA scores this failure mode against your prompt in real time

Free Chrome extension. Analyzes your prompt as you type, flags failure-prone patterns specific to this model, and tells you what to rewrite — before you commit credits to a generation that will fail.

Install free All 105 failure modes

AVA Pro · founders' round

$50 for 6 months of unlimited scoring across all failure modes + personal failure-history dashboard. Locks in $13/mo grandfathered after.

Claim $50 founders