Q:

Why is minecraft telling me to put a close curly bracket in a quote?

So i've indented my command (the command was generated by a program im making to execute multiple commands in one command) and it keeps telling me to put a '}' after the Command:\\" but that segment is in quotes. I've tested the command before i put it through the program.
{
    BlockState:{Name:"stone"}, 
    Time:1, 
    Passengers:
    [
        {
            id:"falling_block", 
            Time:1, 
            BlockState:
            {
                Name:"redstone_block"
            }, 
            Passengers:
            [
                {
                    id:"falling_block", 
                    Time:1, 
                    BlockState:
                    {
                        Name:"activator_rail"
                    }, 
                    Passengers:
                    [
                        {
                            id:"command_block_minecart",
                            Command:"gamerulecommandBlockOutput false"
                        },
                        {
                            id:command_block_minecart,
                            Command:"setblock ~ ~3 ~ command_block{Command:\"summon minecraft:falling_block ~2 ~1.5 ~ {Time:-1200,Passengers:[{id:command_block_minecart,Command:\\"say the 60 seconds are over\\"}], NoGravity:1}\"}"
                        },
                        {id:command_block_minecart,
                            Command:"setblock ~2 ~3 ~ redstone_block"
                        },
                        {
                            id:command_block_minecart,
                            Command:"setblock ~2 ~4 ~ activator_rail"
                        },
                        {
                            id:command_block_minecart,
                            Command:"setblock ~ ~ ~1 command_block{Command:\"fill ~ ~-3 ~-1 ~ ~ ~ air\"}"
                        },
                        {
                            id:command_block_minecart,
                            Command:"setblock ~ ~-1 ~1 redstone_block"
                        },
                        {
                            id:command_block_minecart,
                            Command:"kill @e[type=command_block_minecart,distance=..1]"
                        }
                    ]
                }
            ]
        }
    ]
}

A:

A double backslash will escape the backslash itself, but not the following quote. To have \" in a quote, you need three backslashes:
(...) Command:\\\"say the 60 seconds are over\\\" (...)

