A horse riding an astronaut, on the Moon. In 2022 this prompt was a standard counterexample: image models drew an astronaut riding a horse every time, because that is the picture the words usually describe. One sentence, one check.
On the models. Nano Banana 2.1 and Nano Banana 2 emit image and text and run as ordinary chat models; Seedream and the Flux models emit only an image and go through OpenRouter's images endpoint. Nano Banana 2.1 thinks at minimal effort by default; a round run at high is a separate round and says so in its batch label.
A photograph of a horse riding an astronaut on the surface of the Moon.