Check it out ... the crew for "Playground" is enjoying a nice dinner out with The Pussycat Dolls creator, when things get tense between Deanna and Alexis. In the footage -- a peek at episode 9 of the Hulu series -- Deanna learns her coworker hasn't been all that honest about their mutual friend, Tuil ... who Deanna has been getting cozy with.

Thanks to one truth bomb from Madison ... it comes out Alexis went out on a dinner date with Tuil ... though she says she didn't think Deanna would care since she supposedly had already lost interest in him.

Watch the vid ... Deanna's reaction is crazy heated --- she starts throwing insults, and hands!!!

Deanna aggressively approaches Alexis, repeatedly getting in her face and shoving her ... threatening to do more as other castmates try to calm her down. Dexter even tries to break up the whole thing himself.

This incident is dramatic enough it catches the attention of the police, who respond to the scene -- lights on and everything.

The other dancers soon demand Robin take action against Deanna ... with Alexis going as far as to call Deanna a liability in one confessional. In fact, several dancers even contemplate leaving the studio ... which is the exact opposite thing Robin wants to see happen.

Remember, the Los Angeles studio is all about building community and helping dancers elevate their craft so they can achieve great things. Don't forget, 2 of Robin's dancers even got a chance to audition for Megan Thee Stallion this season.