Ответ:

The error in the code is the indentation in the for loop. The lines after the for loop should be indented to be inside the loop. Here's the corrected code:

```python

import turtle

board = turtle.Turtle()

board.speed(0)

board.color("red")

board.up()

board.goto(-150, 100)

board.down()

board.pensize(5)

for i in range(2):

board.forward(300)

board.right(90)

board.forward(200)

board.right(90)

board.hideturtle()

ball = turtle.Turtle()

ball.shape('circle')

x = 0

dx = 2

while True:

if x > 150 or x < -150:

dx = -dx

x = x + dx

ball.goto(x, 0)

```

This should draw a red rectangle and move a circle-shaped ball back and forth horizontally.