The Israelites didn't mistake the Golden Calf for God either. They had planned a feast to the LORD the following day.
Exodus 32:4 And he received them at their hand, and fashioned it with a graving tool, after he had made it a molten calf: and they said, These be thy gods, O Israel, which brought thee up out of the land of Egypt.
5 And when Aaron saw it, he built an altar before it; and Aaron made proclamation, and said, To morrow is a feast to the LORD.
Aaron and others still knew who the Lord was. Because some of the mixed multitude that accompanied them out of Egypt believed otherwise it messed it up for the entire nation.