The UN Security Council membership increased from the original 11 (as stated in the film) to 15 members in the 1960s.
The UN is made up of many bodies, each with different functions and remits.
Two of the most well-known bodies are the General Assembly and the Security Council.
The other main bodies are the Economic and Social Council (ECOSOC), the Trusteeship Council, the International Court of Justice, and the Secretariat.
It is however more accurate to speak of the UN as a system, because it has evolved into far more than these six organs.
Construction of new UN Headquarters in New York in 1949.
Article 57 & Article 63 of the UN Charter calls for the affiliation with various specialized agencies to deal with particular issues. The General Assembly, the Security Council and ECOSOC also have powers to create separate and subsidiary bodies.
Reform of the Security Council and the veto power of the five permanent members in particular has been hotly debated since the 90s to better reflect today’s geopolitical realities.
Click on this link and read the overview of the United Nations System (pdf).