Thankfully, these reproduction machines all have common traits:
1. Swan-neck tonearm
2. Cheap, stamped brass flower horn.
3. A sharp bend where the horn connects to the tonearm, instead of a smooth curve.
4. Occasionally, the crank will be at an angle instead of at a 90 degree angle. This is because some portable machines had an angled crank to due to their small size.
5. Cheap reproduction "His Master's Voice" decal.
6. Unusual shapes such as circular or octagonal cases.
7. Always have an external horn.
Internal horn machines and portables are always a safe bet. Outside horn disc machines are rare as they were relatively early (1890s-1910s) and were all but obsolete after the decorative "Victrola" internal horn machines become popular in the '10s. Here are some pictures of true machines:
A real outside horn Victor:

Another real outside horn gramophone:

A tabletop internal horn machine:

An upright internal horn machine:

A typical portable:

Another portable:
