sorry about that

sorry about that

Glib or lighthearted recognition of some mistake one has made, regardless of how serious (or not) the mistake may be. Sometimes expressed more colloquially as "sorry 'bout that." A: "Oops, sorry about that. I didn't realize you were still using this computer." B: "Oh, don't worry about it. I'll just log in on a different one." A: "You ruined my entire batch of brownies!" B: "Oh yeah, sorry 'bout that. I needed the oven, though, so I just took them out."
See also: sorry, that
Farlex Dictionary of Idioms.

(I'm) sorry.

an expression used to excuse oneself politely or apologize, especially when one has collided with someone, when one has offended someone, or to ask someone to repeat what has been said. "I'm sorry," I said to the woman I bumped into. I'm sorry, what did you say? I couldn't hear you.

sorry about that

 and sorry 'bout that
sorry; whoops. (A gross understatement, said more as a self-deprecating joke than as an apology.) You spill hot cocoa on my coat, and all you can say is "Sorry 'about that"? When the passenger stepped on my toe, she said, "sorry about that."
See also: sorry, that
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

sorry

and pathetic
mod. pitiful; drawing ridicule or scorn; worthy more of condemnation than pity. (In colloquial use these words are usually used in sarcasm and disgust.) You are one sorry bastard! You are a pathetic person and a pathetic example of a quarterback!

sorry ’bout that

verb
See sorry about that
See also: sorry, that

sorry about that

and sorry ’bout that
interj. sorry; whoops. (A gross understatement, said more as a self-deprecating joke than as an apology.) When the passenger stepped on my toe, she said, “Sorry about that.”
See also: sorry, that
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • sorry ’bout that
  • by mistake
  • and no mistake
  • and no mistake!
  • an honest mistake
  • mistake
  • mistake (someone or something) for (someone or something)
  • mistake for
  • cast a long shadow
  • demur at (something)