Advice on Mammoth CNC Router Build - Steel Framed - 2440mm x 1220mm cutting area!

[JAZZCNC]

Any other glaringly obvious mistakes in the design??

Not glaring but you have gone too far with removing the diagnols but not far enough in other places.?

I would have diagnols at each end of the sides. But would remove the central upright and re-space others on all the Bed support frames.
Would also have a Bed support frame on each side upright and not laid flat in like you have in centre.

The rest looks ok.

EDIT: I would also on the outer End bed supports have diagnols on inside lower beam which fastens to the sides to help hold frame square while setting up and bed frame is fastened. Like this but larger and to suit your design.