The Kelvin scale is used to measure extremely cold temperatures. Zero on the kelvin scale is the coldest temperature possible, it is known as absolute zero, it is the temperature at which all thermal molecular motion ceases.
Joan has a lunch meeting with her mother, Mary Watson. Mary Watson is also the name of John Watson's wife in the Arthur Conan Doyle Sherlock Holmes stories.
77 Kelvins is equal to -321.07 °F (-195.15 °C).
When entering the suspect's warehouse, Sherlock uses his forearm to turn on the light switch to avoid leaving fingerprints/DNA. This action is entirely unnecessary since he had just gloved the hand of that same arm.
The manager of the ice rink is accused of stealing 25 tanks of R22, with a value of $200 per tank. Watson asks if they will find an unaccounted amount of $4,000 in his bank records. 25 tanks at $200 a tank would be $5,000, not $4,000.