Tadmeen
Tadmeen (تضمين, literally "insertion") is a hypothesis which tries to explain away why the Quran sometimes uses wrong prepositions. The explanation is that if a word is used with a wrong preposition, then it's because a different word which can be used with that preposition, was invisibly inserted into the original word.
English analogy
In English we can say "believe in god" and "pray to god". If the Quran was in English and contained "believe to god", it would be an error, because it should be "believe in god". And one way apologists could try to explain it away would be to say that the word "pray" was invisibly inserted into the word "believe" and since "pray" can be used as "pray to", then "believe to" is also correct.
Examples
"Sexual intercourse to your wives" (الرفث إلى نسائكم)
This is 2:187 translated by Muhsin Khan:
It is made lawful for you to have sexual relations (الرفث) with (إلى) your wives on the night of As-Saum (the fasts)..
The word إلى actually means "to". The word "with" would be مع or ب. And it's not correct in Arabic to say الرفث إلى ("sexual intercourse to [someone]") as the Quran says it. ِAnd the apologetic explanation is that it's a case of tadmeen (insertion) and that the word أفضى (to go) was inserted into the word الرفث ("sexual intercourse") and since it's correct to say أفضى إلى ("go to"), then الرفث إلى ("sexual intercourse to") is also correct.
The translation Sahih International even translates it as "go to" and puts "for sexual relations" in brackets, although in Arabic the verb "go" is not present at all and the word "sexual intercourse" is:
It has been made permissible for you the night preceding fasting to go to your wives [for sexual relations]..