Soon after the nuclear launch had started, Yuno and his friend Helloo conveniently come rushing in all guns blazing.

Yuno said that the scanner found it but I know for a fact that the scanner he shot at the cinema wall outside did not go off and it made the usual sound not the "affirmative" sound.

Also Yuno was in noclip at the time and nocliped up to look over the black props and to find the entity which was the nuke.