There are a few scenarios that may not be immediately obvious, and can vary by location and appearances.
There is the obvious of being seen to be carrying an offensive weapon.
You may be stopped by traffic officers whether that is due to the weapon being seen or for other reasons, then they notice it during the stop.
However you may be reported by any member of the public, and an appropriate response begin called out
Best case scenario is a chat and some advice
Bit worse is a more enforced response that can vary based on your attitude/reactions and how they are primed. There may be other issues going on to heighten their response
Things can go bad very quickly due to other factors, such as being shot dead in an armed response due to being Scottish in London with a table leg in a carrier bag. This was in the height of the IRAs London campaign and members of the public reporting a man with an accent and a sawn off shot gun. The wrong reaction in the heat of the moment ended up with a dead innocent man
We also have the case of armed police being commended for not shooting a teenager who pulled out their BB gun ‘jokingly’ from their trousers pointed back at the armed police. This idiot remains alive because a policeman hesitated in disbelief. If they were wrong then the officer would have died
There is also another possibility, terrorism remains a threat, both classic organized and modern individuals. To both an airsofter who travels partly dressed, and with military looking gear maybe confused with a valuable target.
You will see off duty / traveling service personnel out and about who have the signs. They are advised based on security threats on what is and is not wise. Mixed dress is a no no, but regularly happens.
An airsofter can unwittingly come to the attention of undesirables as an opportunistic target, and if they are mistaken it’s still worth the bad publicity.
The majority of the time nobody pays any attention. But the odd fancy dress does get reported
Locally we had an armed response due to an AK47 being seen.
The manager of the local vodka bar slept in the bar after the New Year’s Eve party. In the morning he pottered around clearing up, put his comedy fancy dress ak47 in his car boot, pottered around some more, then found himself being called out by megaphone and the street full of armed police
Bag and cover your kit
If you have too much to bag / transport for your method of travel then thin down the kit.