as a disclaimer - all I say below may not be technically right or correct.
but...
I found that overexposing a lot, somewhat helps in low-light situations.
For example, your scene looks correctly exposed at iso 400. Change it iso 1600, and you will get some highlights clipped and wrong exposure, but in post you will bring down the exposure -2 stops. Also the noise. It becomes a lot less visible... But try it at your own risk

Also, color noise is mostly red, so you can desaturate deep reds, and try to use less contrast and less saturation for night scenes overall, it will make noise less noticeable.
Try darkframe subtraction, maybe it will help too...
And record in 12 or 14 bits, 10 bits could be too noisy.
what else... you know the rule shutter speed should be 180 degrees, but if there is not much movement in a scene, you can use exposure override and set the exposure to 1/25 seconds (while filming at 24 fps), it is almost 360 degree shutter, but it is +1 stop more light. But watch for the lights flicker (60hz or 50hz frequency).
And remember that noise is really visible in the dark areas, so if your scene looking well-lit, then high iso is OK. But you don't have much room to maneuver in darker scenes. So you can just leave them dark as part of the style..
Anyway, you don't want to turn night into day with these not so suitable for night shooting cameras.. you have to keep all these things in mind when shooting in low-light.