The Oxford Dictionary of Philosophy entry for 'entity' says:
A real thing. Entity realism is the term associated with the
contemporary Canadian philosopher Ian Hacking, whereby the the issue
of scientific realism is not one of the truth or falsity of scientific
theories, but of the real existence of the things which scientist
The ascii characters below have been manipulated, so the frog is an entity.
( >__< )
^^ ~~ ^^
If the arrangement was accidental, but you noticed the frog then your mind would have manipulated the arrangement into an image. So again, you could say the frog is a entity. As long as you are a scientist. ;-)
If the arrangement was accidental, and you didn't notice anything, the frog would not be an entity, for you. Someone else might notice it though. In these cases entity is the same as existence.
Ordinarily one would not think of an abstract phenomenon such as confusion as an entity. However, if confusion is the subject of an enquiry or experiment -- manipulable and manipulated -- then even it can be an entity.
But in general, no, existence does not imply entity.