Fantastic Four: World's Greatest Heroes (2006)

S1E6 World's Tiniest Heroes

During a mishap with Reed's miniaturization experiment, the team finds themselves shrunk down to a tiny size, facing perilous situations. Things take a turn for the worse when H.E.R.B.I.E. mistakenly perceives them as pests and sets out to eliminate them, putting their lives in jeopardy.