Correction of figure in galley proofs in Elsevier journal
Is the error trivial (i.e. does not need to be peer reviewed, no reasonable person would object) or not? If it is trivial, then don't worry about it now and correct it during galley proofs. A sufficiently obvious error might even be spotted by the publisher when they do copyediting. If it is not trivial then let the editor know, since they might need to get the reviewer to check it again.