In the episode 5 of Saint Seiya we can see Momo briefly between the public in the tournement where the knights are figthing to win the golden armor in the firsts episodes. This scene takes place a little after Pegasus defeats Dragon and he is declared the winner of the match. However, a few moments later he faints and fell to the floor. It's in this moment when the camera shows the amazed faces of the audience and we can see Momo at the right. In the image below we can see Momo as the camera was panning over the scene.

Thanks to Cristian for reporting this cameo and thanks to Orlando for sending me this episode of Saint Seiya.

In the sequence were the starrings ride on a bike, they run into another rider who has an helmet with a face of Momo painted. In the helmet there's written the name "Motoigi", for Hiroaki Motoigi, a member of the staff of this OVA. As a side note, in the movie of Robotech were they use these footage of Megazone, this scene is not visible even advancing frame by frame, probably in the conversion some cels were lost.

Thanks to Esteban D'Andrea for reporting and explaining this scene, as well as the image provided.

In the episode 7 "No need for festivals" we can see Sasami and Ryoko having fun at the festival. We can see behind Sasami a stand with masks, and one of them is a mask of Minky Momo, as the close up shows.

Thanks to Alejandro Cuadros for reporting this scene.