Eggcorns (Wikipedia / YouTube video by RobWords) are language mistakes that sometimes take over and change the spelling and perhaps even the meaning of a word. This is rare in German because there’s fewer homophones but in this episode of Wort der Woche, DW explains how “munttot” became “mundtot”. Available as audio or transcript.
There is also Armbrust (crossbow) which comes from arcubalista but literally means arm + chest