Then there are all those mock antonyms that involve negafixes, like fancy vs. infancy (as suggested by the antonyms sane vs. insane.) There are many more than those listed here, but you get the idea. See if you can come up with more.
atomic vs. anatomic (as in aerobic vs. anaerobic)
band vs. contraband (as in indicate vs. contraindicate)
basement vs. abasement (as in moral vs. amoral)
chief vs. mischief (as in inform vs. misinform)
continent vs.incontinent (as in sane vs. insane)
dote vs. antidote (as in freeze vs. antifreeze)
due vs.subdue (as in culture vs. subculture)
esthetic vs. anesthetic (as in aerobic vs. anaerobic)
fancy vs. infancy (as in sane vs. insane)
gent vs. agent (as in moral vs. amoral)
giving vs. misgiving (as in inform vs. misinform)
grade vs. retrograde (as in active vs. retroactive)
less vs. unless (as in sure vs. unsure)
lustrate vs. illustrate (as in legal vs. illegal)
nomination vs. denomination (as in sensitizevs. desensitize)
note vs. denote (as in sensitize vs. desensitize)
ort vs. abort(as in normal vs. abnormal)
patch vs. dispatch (as in assemble vs. disassemble)
plus vs. nonplus (as in fiction vs. nonfiction)
prove vs. improve (as in mature vs. immature)
sect vs. insect (as in sane vs. insane)
side vs. subside (as in culture vs. subculture)
solve vs. absolve (as in normal vs. abnormal)
stand vs. understand (as in rate vs. underrate)
top vs. countertop (as in intuitive vs. counterintuitive)
traction vs. subtraction (as in culture vs. subculture)