get one's wires crossed

get one's wires crossed ( be confused or mistaken about something) — перепутаться в голове; все перепутать; переклинить

Example 1: I got my wires crossed and called his home phone instead of his work phone. (Wictionary)

Example 2: Jim said there is a meeting today. Don't we have one? — No. The meeting's tomorrow. I guess he's got his wires crossed. — Джим сказал, сегодня совещание. Разве нет? — Нет. Совещание завтра. Похоже, у него всё в голове перепуталось.

=====
This expression transfers a wrongly wired telephone or telegraph connection to human misunderstanding.

Сf.
[ум за разум заходит]
[in over one's head]
[каша в голове]
[мозговой затор]