The document discusses 101 mistakes that can be made when configuring Kafka. Some of the key mistakes discussed include: 1) Not distinguishing between internal and external data when publishing to Kafka topics 2) Not defining schemas for Kafka data externally such as in a schema registry 3) Using the same Kafka configuration for all topics and clients instead of tailoring configurations based on individual needs 4) Defaulting all topics to 128 partitions without considering actual throughput needs 5) Deploying Kafka in production on overloaded nodes that were intended for proof-of-concept use only