What happens if you forget to install one spark plug?

So my Dad and I were changing the spark plugs in my car and we got kinda distracted and somehow I forgot to put one of the spark plugs in the hole. So after I plugged everything up there were only 3 plugs in the engine. When we started it up it misfired but it made an extremely loud pop and I saw a like a mini

So my Dad and I were changing the spark plugs in my car and we got kinda distracted and somehow I forgot to put one of the spark plugs in the hole. So after I plugged everything up there were only 3 plugs in the engine. When we started it up it misfired but it made an extremely loud pop and I saw a like a mini explosion near one of the plug holes. After we realized our mistake we put the plug in and the engine ran but when I turned it off it made like a beeping noise. Do you think there s an issue, what should I do. Thank you in advance.

Other answer:

Andrew Rivera:
Just put the damn spark plug back in and go drive your car.
Poppy:
LMFAO, you and dad need to not be doing this.
Changing plugs is remove one, replace it. Remove another, emplacement it. Until all are done. We DO NOT remove all and replace. Leave it go and see for now. Hire this done for future tune ups.
Ron:
It made a beeping noise after you turned it off?
Pilsner Man:
No one can be this stupid, seriously?