Continuity mistake: When Anne breaks up with Eddie on the sidewalk right after they get fired from their jobs, she approaches him and drops the box she is carrying. A ceramic mug falls out of the box. There is both visual and audible confirmation. After putting her ring in his shirt pocket, she bends to pick up the empty box and proceeds to walk away without also retrieving the missing contents. (00:14:45)
Plot hole: At the angle of descent and the speed it was traveling (still burning from reentry even), when the space shuttle crashed in the opening of the film, it would not have left much of anything behind. The kinetic explosion that would have resulted would have downed the forest around it for a good distance leaving a crater, and the clean up crews would have been lucky to find any piece of the ship itself still intact bigger than a football. Much less been able to find any discernible remains of the crew. Yet bodies were being taken out in still relatively good condition. And probably most unbelievable is that the glass containers holding the Symbiotes were not even broken.
Plot hole: The Riot symbiote inhabits the body of the paramedic immediately after the crash at the beginning, then goes into the body of an old woman who goes to the airport and proceeds to take control of a little girl who's going on a flight to San Fransisco. Riot then takes over Carlton Drake's body. The entirety of these events would need to have taken six months, for it to be consistent with the timeline of the rest of the film.
Factual error: When Venom is standing on top of a tall building, he falls off as a jet airliner passes over head with its loud engines hurting the Symbiote with its noise. The airliner passes very close to the building. But this would not happen as it is as FAA regulations are that an aircraft can not operate within 500 feet of any structure. And an airfield/airport would be positioned so that jets would not violate this decree on their landing descent.
Revealing mistake: When the ambulance featuring the first Venom incarnation crashes it comes to a very sudden stop, like a piece of metal tipped over onto a magnet instead of sliding under its own momentum. Likely because they didn't animate the transition between the CGI of the crash and the stationary position of the set properly.