I see the same things Jonathan does but I also see other few factors that you may want to consider.? Some regards build design, some practicle usage considerations.

#1 The distance from the lower bed to spindle appears to be approx 100mm.? You also have drawn a sub base which would guess being 19mm MDF spoil board.? That leaves 81mm total distance for material and tooling. Basicly giving a Max tooling length and material thru cut of capabilty of 40mm which hisn't much.! . Most drill flutes alone can be longer than 40mm, even a short endmill will stickout from spindle 20-30mm so unless you only plan on cutting thin material I would look to increase in height in this department.

#2 Consider how you will mount the X axis bearings to the plates and still have access to the screws.? The way you have it drawn at the minute the profile will cover the holes unless you install the profile after. Idealy you would want the bearing plate,profile and gantry sides to all be bolted together for Max strength but the way you have it at the minute this wont be possible and way it is will make setting up the machine regards squareness etc a pain.
An easy fix would be to have 2 bearing plates, one which mounts to the bearings the other part of the whole gantry which bolts to the bearing plate.

#3 The bed supports all run length ways.? I would run all inner or at least one central width ways with 2 length ways offset as the shorter length beams will be stronger reducing bed flex and beefing the frame up in all direstions and esp the long length.

#4 Check the linear rails base will fit the profile width, some are wide and the mounting holes may fall in the wrong place were there's no much material in the profile or directly inline with profile internal structure making drilling amd tapping very difficult.?
Often it's better to mount a wider plate to the profile then mount the rails to the plate, it certainly makes drilling and tapping far easier.

Hope these things are usefull.