I'm a developer for machine vision systems. I was working with a client in order to define the scope of the new systems.
Client: Well we have 4 references that need to be inspected.
Me: Alright can we get some samples to start developing the software and design the inspection strategy?
Client: Sure, I'll just note that down and we will write the scope on the contract.
As I'm part of the engineering team the contract never reached our hands; it only goes through the Commercial team. Around three months later without hearing from the client or the project, we get several boxes with the samples. But inside them, there were twenty different samples to inspect!
When confronted, the commercial team said that the contract was already signed for this project and that they were gonna talk with the client. A few days later we (the engineering team) were invited to a meeting to discuss the change of scope.
Client: What change of scope are you talking about?
Me: You stated there would be only four references to inspect, we got a box with ~20 different references...
Client: Oh no no, each reference has 5 different stylings, the scope is still the same.
Said differences in styling meant that the product had the same capacity but the morphology was completely different. This for us meant several weeks more to develop the inspection strategy for the newly added 16 different products.
Sadly to say this was just the first misstep into this project. The deadline was not moved.