Between 04:20 and 05:17, the Brain People can first be seen with tentacles crawling on a log.
Seconds later the Brain People is shown being pulled upwards toward the log, without tentacles.
At 37:09, when the Evil Alien takes off his hat, the "brain" is clearly and obviously a shower cap with a limited amount of brain like ridges and ears painted on.
At minute 13:45, the Brain is clearly shown being pulled along by a string, which is also wrapped around the brain.