The speech bubble says "I bet she has forgot somethin".
I think it would be better if it said either "I bet she's forgotten something" or "I bet she forgot something". It's just a more natural speech pattern. Not many people would say "she has" in normal speech, unless they wanted to emphasize something a person had actually done. In that case the emphasis would be indicated in text by italicizing the word has; "I bet she has forgotten something".
Come to think of it, it might be better if it were a thought bubble rather than a speech bubble, because it seems more like a private thought than the sort of thing one would say out loud.