あれ？この曲・・・。プレイリストが一周してるな。

that (indicating something distant from both speaker and listener (in space, time or psychologically), or something understood without naming it directly); that person (used to refer to one's equals or inferiors); over there; down there (i.e. one's genitals); period; menses; hey (expression of surprise, suspicion, etc.); huh?; eh?; that (something mentioned before which is distant psychologically or in terms of time)

this (something or someone close to the speaker (including the speaker), or ideas expressed by the speaker)

tune; piece of music

middle dot (typographical symbol used between parallel terms, names in katakana, etc.); full-stop mark at mid-character height; interpoint (interword separation)

playlist

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

once around; a revolution; a lap; a turn; a round; one full year

(sentence end, mainly masc.) indicates emotion or emphasis; (used with masu stem verb) command; (used with dictionary form verb) prohibition