These marks are obvious on the original and usually still physically present. On a reproduction they can often be seen but they are flat photographic images. Most early maps were coloured by hand and brush strokes can often be discerned. Reproductions usually use printed halftones and the small dot patterns can be seen with a magnifying glass. Reproductions that are not intended to deceive usually identify themselves with fine print that includes modern dates or printing houses.
Early paper is made with a high rag content.
Chain marks, watermarks and similar features can be seen in the bright light. Reproductions on modern paper lack such features. Old paper usually looks old. The edges will be slightly worn and perhaps soiled. It always makes sense to keep any work on paper out of direct sunlight and use UV filtering glas.