There are mobile units for producing hydrogen for balloons used in artillery tracking. A typical unit can be seen here. The units Marconi builds can be seen here. Marconi is the outfit that shipped such units to Iraq from Britain during the Thatcher administration.

Note that neither unit resembles in any way the trailers found in Iraq.

I have never seen any unit designed for mobile production of storable missile propellants. Ever.

I can think of no reason why this would be necessary. Many missiles have solid fuel, and are filled at the factories. Few if any military missiles use cryogenic propellants, and those I know of were silo-based ICBMs.

Missiles with storable propellants are also usually filled at the plant, or from simple storage tanks, which are sometimes mobile. With the exception of kerosene, which certainly is not produced from scratch in little trailers, storable rocket propellants are very nasty customers, corrosive, poisonous, unstable, or sometimes all three (UDMH, IRFNA*, and others).

It is inconceivable that there would be mobile units for manufacturing these liquids from raw materials on site, and it would not fit in a few small trailers anyway.

These are called facts, and some of those arguing with me aren't the least bit interested in them. When, or if, one of them responds to this post, you will note that they will not address specifically any of the above but will go off on some tangent.

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*used in SCUDs