How to summon a falling_block (command_block) that is facing east?

I've tried:

/summon falling_block {Block:command_block 2,Time:1}

but it says:

[16:09:26] Data tag parsing failed: Expected '}' but got '2' at: {Block:command_block 2<--[HERE]

If I use:

/summon falling_block {Block:command_block,Time:1}

it succeeds but then it is facing down.

You have to specify the block data in order to rotate it. In your case, east would be 5. You do this by adding Data to your command. I also added coordinate information.

/summon falling_block ~ ~1 ~1 {Block:"minecraft:command_block",Time:1,Data:5}

Here is a list of block data from the wiki linked above:

• 0: facing down
• 1: facing up
• 2: facing north
• 3: facing south
• 4: facing west
• 5: facing east